1.6: Interdependence of Living Things - Biology

What other species do you need to survive?

Species cannot live alone. All life needs other life to survive. Here surgeon fish are feeding on the algae growth on this turtle shell, a classic example of two species needing each other. This is an example of a symbiotic relationship.

Interdependence of Living Things

All living things depend on their environment to supply them with what they need, including food, water, and shelter. Their environment consists of physical factors—such as soil, air, and temperature—and also of other organisms. An organism is an individual living thing. Many living things interact with other organisms in their environment. In fact, they may need other organisms in order to survive. This is known as interdependence. For example, living things that cannot make their own food must eat other organisms for food. Other interactions between living things include symbiosis and competition.


Symbiosis is a close relationship between organisms of different species in which at least one of the organisms benefits. The other organism may also benefit, it may be unaffected by the relationship, or it may be harmed by the relationship. Figure below shows an example of symbiosis. The birds in the picture are able to pick out food from the fur of the deer. The deer won't eat the birds. In fact, the deer knowingly lets the birds rest on it. What, if anything, do you think the deer gets out of the relationship?

A flock of starlings looks out, before searching for parasites on a red deer stag.


Competition is a relationship between living things that depend on the same resources. The resources may be food, water, or anything else they both need. Competition occurs whenever they both try to get the same resources in the same place and at the same time. The two organisms are likely to come into conflict, and the organism with better adaptations may win out over the other organism.


  • All living things depend on their environment to supply them with what they need, including food, water, and shelter.
  • Symbiosis is a close relationship between organisms of different species in which at least one of the organisms benefits.
  • Competition is a relationship between living things that depend on the same resources.

Explore More

Use this resource to answer the questions that follow.

  • → Non-Majors Biology → Search: Interactions Within Communities
  1. How do organisms within a community interact with each other?
  2. Describe and give examples of the two types of competition.
  3. How may predation benefit the prey population?
  4. Describe the various types of symbiotic relationships.
  5. Describe a type of mutualistic relationship involving humans.


  1. What is meant by interdependence?
  2. Describe an example of a way that you depend on other living things.
  3. Compare and contrast symbiosis and competition.
  4. Give three examples of resources organisms may compete for.

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Little 1st Grade SCIENCE Thinkers Little 1st Grade SCIENCE Thinkers is a complete science curriculum specifically for first grade. It's everything you need to introduce, teach, practice, and assess your students. It incorporates both the NGSS standards as well as many state standards for 1st grade science. This curriculum was completely researched, designed, and created by Karen Jones. teaches your little learners all about how living things grow and survive in our world. It includes many engaging investigations and experiences for your class. It includes lessons on these topics: Living and Nonliving Things Interdependence of Living Things COMPONENTS OF THE UNIT: -6 printable/projectable Books for Read-Alouds -Step-by-step, Scripted Lesson Plans (Twelve, 30-minute lesson plans in all) -Essential Question and Learning Target Posters -Assessment and Rubric for scoring -A COMPLETE unit PowerPoint to guide your teaching during each and every lesson (all books, targets, activity and workbook pages are included in the PowerPoint to help you save paper) Lesson 1: LIVING AND NONLIVING THINGS Lesson 2: HOW PARTS OF LIVING THINGS HELP THEM SURVIVE Lesson 3: BIOMIMICRY INVESTIGATION Lesson 4: OFFSPRING OF LIVING THINGS Lesson 5: INHERITED TRAITS Lesson 6: INHERITED TRAITS INVESTIGATION Lesson 7: INTERDEPENDENCE OF PLANTS AND ANIMALS Lesson 9: SCIENCE STATIONS Lesson 10: SCIENCE STATIONS Lesson 12: UNIT ASSESSMENT *Please download the preview to see all that is included, including samples of everything!* Living Things Vs. Nonliving Things Lesson Plan

Students will be able to compare living and nonliving things.

Students will be able to identify characteristics of living and nonliving things.

Students will be able to identify plants, animals and people as living things.

Lesson Essential Question(s)


120 minutes / 2 large group lessons


The Magic School Bus Plants Seeds: A Book About How Living Things Grow by Joanna Cole and John Speirs also can also be viewed on discovery education united streaming

Sets of Pictures of living and nonliving things for group activity such as cat, car, squirrel, bicycle, bus, blocks, board game, flower, tree, fly, airplane, bee, child, adult

A gold fish in its habitat and a large river rock

Suggested Instructional Strategies

By the end of this lesson, students will be able to compare living and nonliving things by identifying characteristics of both living and nonliving things. Students will also be able to identify plants, animals, and people as living things.

Students become engaged by assessing prior knowledge by comparing and contrasting various pictures and seeking a way to sort them into 2 groups.

Students watch video clips of living things while identifying living and nonliving things viewed in the video. In a second activity students listen and discuss a story that address the characteristics of living things. In a final activity students observe two distinct objects ( living and nonliving) throughout the day and part of the next writing and drawing in their journal.

Use formative assessment techniques to determine which students need additional practice or reteaching. Work with these students individually or in small groups to reinforce understanding of the new vocabulary.

Observation of students as they participate in activities can be used to assess understanding. The completed journaling of their observation and the completed picture and statement activity, and the participation of the whole class review assessment.

This lesson may be tailored to individual needs by pairing struggling students with more capable ones. The lesson provides opportunities for students to learn through visual and auditory activities.

Students work in a small sgroup, in a large group, and individually to complete the activities of this lesson.

Instructional Procedures

To assess prior knowledge about living and non-living things, randomly display pictures such as the following along the board ledge: car, cat, squirrel, bicycle, bus, blocks, board game, flower, tree, fly, airplane, bee, child, adult. Place students into small groups of 3 or 4. Pass out sets of pictures to each group. Ask students to think of a way to sort all the pictures into just two groups (things that are living and things that are not living). Help them also see that the "living things" are plants, animals, or people

Ask the guiding questions:

Talk about the difference between living and non-living things by reviewing their responses to the game.

Write on a chalkboard or a big piece of paper, &ldquoLiving&rdquo and &ldquoNot Living.&rdquo Share ideas about things that are living and not living and write them down in the appropriate column.

Take a look at all the living things. Share ideas about what they all have in common. Lead the discussion to identifying principles of all living things including: use food, give off wastes, grow, and can reproduce offspring like themselves. to watch clips of living things. After viewing the website, have students name things that are non-living. Record answers on the interactive smart board. This website contains many video clips of living things.

Read The Magic School Bus Plants Seeds : A Book About How Living Things Grow to students. Have students discuss the characteristics of living things. Record their responses on the interactive smartboardboard.

Set up and display a goldfish habitat in a fishbowl. Place a large river rock beside the fishbowl. Have the class observe the rock and the goldfish throughout the day drawing pictures of what they are observing.

Ask guiding questions above: What is alive? What is not alive? Encourage students to share their journal pictures describe and compare how each looked and acted, and share what they observed. Rock and goldfish
Remind students that when they compare, they tell how things are alike and different.
Discuss what makes each living or non-living. Have students list the three types of living things: animals, plants, and people. Have them share what living things need to survive.
Chart their responses on interactive smartboard

Provide art paper for students to draw what they've observed. Have them write a statement about what makes one or both living or nonliving. Assist students with statements.

As a class, take the Living Things quiz on the website

Discuss the answers as the class is taking the quiz.
After taking the quiz, give students the assessment activity individually.

Summary of Biology Definitions

Diffusion – the passive movement of particles from a region of high concentration to a region of low concentration.

Osmosis – the passive movement of water molecules, across a partially permeable membrane, from a region of lower solute concentration to a region of higher solute concentration.

3.2.1 – Distinguish between organic and inorganic compounds

Organic compounds are based on carbon and can be found in living things. Exceptions CO. These are classed as non-organic carbon. Three types of organic compounds widely found in living organisms are lipids, proteins and carbohydrates.

Inorganic compounds are any compounds that do not fall into the category of organic compounds.

3.6.1 – Define enzyme and active site

Enzyme – A biological catalyst made of globular protein

Active Site -The region of an enzyme molecule surface where the substrate molecule binds and catalysis occurs

3.6.4 – Define denaturation

A structural change in a protein that alters its shape and results in a loss of biological properties. This can be caused by pH or temperature.

3.7.1 – Define cell respiration

Cell respiration is the controlled release of energy from organic compounds in cells in the form of ATP

4.1.2 – Define gene, allele and genome

Gene – A gene is a heritable factor that controls a specific characteristic

Allele – An allele is a specific form of a gene, differing for other alleles by one or a few bases only. They occupy the same gene locus as the other alleles on the gene

Genome – The whole of the genetic information of an organism

4.1.3 – Define gene mutation

A gene mutation is a change in the base sequence of an allele

4.2.2 – Define homologous chromosomes

Chromosomes in a diploid cell which contain the same sequence of genes, but are derived from different parents.

4.3.1 – Define genotype, phenotype, dominant allele, recessive allele, codominant alleles, locus, homozygous, heterozygous, carrier and test cross

Genotype – The alleles of an organism

Phenotype – The characteristics of an organism

Dominant Allele – An allele that has the same effect on the phenotype whether it is present in the homozygous or heterozygous state

Recessive Allele – An allele that only has an effect on the phenotype when present in the homozygous state

Codominant Alleles – Pairs of alleles that both affect the phenotype when present in a heterozygote

Locus – The particular position on homologous chromosomes of a gene

Homozygous – Having two identical alleles of a gene

Heterozygous – Having two different alleles of a gene

Carrier – An individual that has one copy of a recessive allele that causes a genetic disease in individuals that are homozygous for this allele

Test Cross – Testing a suspected heterozygote by crossing it with a known homozygous recessive

4.3.7 – Define sex linkage

Genes carried on only one of the sex chromosomes and which therefore show a different pattern of inheritance in crosses where the male carries the gene from where the female carries the gene

4.4.11 – Define clone

A group of genetically identical organisms or a group of cells derived from a single parent cell

5.1.1 – Define species, habitat, population, community, ecosystem and ecology

Species – A group of organisms that can interbreed and produce fertile offspring.

Habitat – The environment in which a species normally lives or the location of a living organism.

Population – A group of organisms of the same species who live in the same area at the same time.

Community – A group of populations living and interacting with each other in the same area.

Ecosystem – A community and its abiotic environment.

Ecology – The study of relationships between living organisms and their environment

5.1.2 – Distinguish between autotroph and heterotroph

Autotroph – An organism that synthesizes its organic molecules from simple inorganic substances

Heterotroph – An organism that obtains organic molecules from other organisms

5.1.3 – Distinguish between consumers, detritivores and saprotrophs

Consumers – An organism that ingests other organic matter that is living or recently killed

Detritivore – An organism that ingests non-living organic matter, also known as a decomposer.

Saprotroph – An organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion

5.1.6 – Define trophic level

The trophic level of an organism defines the feeding relationship of that organism to other organisms in a food chain. In a food web, a consumer can occupy a number of different trophic levels, depending on which organism is the prey.

5.4.1 – Define evolution

Evolution is the cumulative change in the heritable characteristics of a population.

6.1.6 – Distinguish between absorption and assimilation

Absorption – Soluble products of digestion are absorbed into the blood circulation system, or the lymphatic system if they are fats droplets.

Assimilation – Products of digestion are absorbed into the cells from the blood to be stored or used within the tissues.

6.3.1 – Define pathogen

An organism or virus that causes a disease or sickness. These are usually microorganisms.

6.3.5 – Distinguish between antigen and antibodies

Antigen – A foreign substance that stimulates the production of antibodies. It is recognised by the immune system, triggering this immune response.

Antibodies – Proteins, immunoglobin, that recognise and bind to specific antigens. These have a T or Y shape made from polypeptide chains.

6.4.1 – Distinguish between ventilation, gas exchange and cell respiration

Ventilation – The pumping mechanism that moves air in and out of the lungs efficiently, thereby maintaining the concentration gradient for diffusion.

Gas Exchange – The exchange of gases between an organism and its surroundings, including the uptake of oxygen and the release of carbon dioxide in animals and plants.

Cell Respiration – The controlled release of energy in the form of ATP from organic compounds in cells. It is a continuous process in all cells.

6.5.4 – Define resting potential and action potential (depolarisation and repolarisation)

Resting Potential – An electrical potential across a cell membrane when not conducting an impulse

Action Potential – The localised reversal, or depolarisation, and then restoration, or repolarisation, of electrical potential between the inside and outside of a neuron as the impulse moves along it

7.3.2 – Distinguish between the sense and antisense strands of DNA

Sense strand – The coding strand that carries the promoter sequence of bases to which RNA polymerase binds and begins transcription. It has the same base sequence as mRNA, except with uracil instead of thymine. It also carries the terminator sequence of bases at the end of each gene, causing RNA polymerase to stop transcription

Antisense strand – The template strand for transcription by complementary base pairing. It has the same base sequence as tRNA with uracil instead of thymine.

9.2.5 – Define transpiration

Transpiration is the loss of water vapour from the leaves and stems of plants

9.3.2 – Distinguish between pollination, fertilisation and seed dispersal

Pollination – The transfer of pollen grains from the mature anther to the receptive stigma

Fertilisation – The fusion of the male gamete with the female gamete to form a zygote

Seed Dispersal – Seeds are moved away moved away from the vicinity of the parental plant before germination to reduce competition for limited resources. Mechanisms for this include fruits, winds, water and animals.

10.2.2 – Distinguish between autosomes and sex chromosomes

Autosome – A chromosome that is not a sex-chromosome. They do not vary depending on gender

Sex Chromosome – A chromosome which determines sex rather than other body (soma) characteristics

10.3.1 – Define polygenic inheritance

Inheritance of phenotypic characters (such as height, eye colour in humans) that are determined by the collective effects of several genes – a single characteristic that is controlled by two or more genes

11.3.1 – Define excretion

The removal of the waste products of metabolic pathways from the body

11.3.5 – Define osmoregulation

The control of the water balance of the blood, tissue or cytoplasm of a living organism.

Current Species Diversity

Despite considerable effort, knowledge of the species that inhabit the planet is limited. A recent estimate suggests that the eukaryote species for which science has names, about 1.5 million species, account for less than 20 percent of the total number of eukaryote species present on the planet (8.7 million species, by one estimate). Estimates of numbers of prokaryotic species are largely guesses, but biologists agree that science has only just begun to catalog their diversity. Even with what is known, there is no centralized repository of names or samples of the described species therefore, there is no way to be sure that the 1.5 million descriptions is an accurate number. It is a best guess based on the opinions of experts on different taxonomic groups. Given that Earth is losing species at an accelerating pace, science knows little about what is being lost. [Figure 1] presents recent estimates of biodiversity in different groups.

This table shows the estimated number of species by taxonomic group—including both described (named and studied) and predicted (yet to be named) species.
Estimated Numbers of Described and Predicted species
Source: Mora et al 2011 Source: Chapman 2009 Source: Groombridge and Jenkins 2002
Described Predicted Described Predicted Described Predicted
Animals 1,124,516 9,920,000 1,424,153 6,836,330 1,225,500 10,820,000
Photosynthetic protists 17,892 34,900 25,044 200,500
Fungi 44,368 616,320 98,998 1,500,000 72,000 1,500,000
Plants 224,244 314,600 310,129 390,800 270,000 320,000
Non-photosynthetic protists 16,236 72,800 28,871 1,000,000 80,000 600,000
Prokaryotes 10,307 1,000,000 10,175
Total 1,438,769 10,960,000 1,897,502 10,897,630 1,657,675 13,240,000

There are various initiatives to catalog described species in accessible and more organized ways, and the internet is facilitating that effort. Nevertheless, at the current rate of species description, which according to the State of Observed Species 1 reports is 17,000–20,000 new species a year, it would take close to 500 years to describe all of the species currently in existence. The task, however, is becoming increasingly impossible over time as extinction removes species from Earth faster than they can be described.

Naming and counting species may seem an unimportant pursuit given the other needs of humanity, but it is not simply an accounting. Describing species is a complex process by which biologists determine an organism’s unique characteristics and whether or not that organism belongs to any other described species. It allows biologists to find and recognize the species after the initial discovery to follow up on questions about its biology. That subsequent research will produce the discoveries that make the species valuable to humans and to our ecosystems. Without a name and description, a species cannot be studied in depth and in a coordinated way by multiple scientists.

The living world can be organized into different levels. For example, many individual organisms can be organized into the following levels:

  • Cell: Basic unit of structure and function of all living things.
  • Tissue: Group of cells of the same kind.
  • Organ: Structure composed of one or more types of tissues. The tissues of an organ work together to perfume a specific function. Human organs include the brain, stomach, kidney, and liver. Plant organs include roots, stems, and leaves.
  • Organ system: Group of organs that work together to perform a certain function. Examples of organ systems in a human include the skeletal, nervous, and reproductive systems.
  • Organism: Individual living thing that may be made up of one or more organ systems.

Examples of these levels of organization are shown in the figure below.

An individual mouse is made up of several organ systems. The system shown here is the digestive system, which breaks down food into a form that cells can use. One of the organs of the digestive system is the stomach. The stomach, in turn, consists of different types of tissues. Each type of tissue is made up of cells of the same type.

There are also levels of organization above the individual organism. These levels are illustrated in the figure below.

  • Organisms of the same species that live in the same area make up a population. For example, all of the goldfish living in the same area make up a goldfish population.
  • All of the populations that live in the same area make up a community. The community that includes the goldfish population also includes the populations of other fish, coral, and other organisms.
  • An ecosystem consists of all the living things (biotic factors) in a given area, together with the nonliving environment (abiotic factors). The nonliving environment includes water, sunlight, soil, and other physical factors.
  • A group of similar ecosystems with the same general type of physical environment is called a biome.
  • The biosphere is the part of Earth where all life exists, including all the land, water, and air where living things can be found. The biosphere consists of many different biomes.

This picture shows the levels of organization in nature, from the individual organism to the biosphere.

Diversity of Life

Life on Earth is very diverse. The diversity of living things is called biodiversity. A measure of Earth’s biodiversity is the number of different species of organisms that live on Earth. At least 10 million different species live on Earth today. They are commonly grouped into six different kingdoms. Examples of organisms within each kingdom are shown in the figure below.

Food Webs

The most easily understood method of ecological interdependence is a brutish one: living things eat other living things to survive. The predator and prey relationship was one of the first feeding relationships that scientists understood. In the feeding relationship, predators were seen as being at the top of a food chain. As ecology has grown as a field, so has the understanding of feeding relationships. The concept of food cycle arose to account for the fact that all organisms, including predators, die, and are consumed other organisms like insects and bacteria. The recognition that food cycles are linked led to the development of the concept of a food web, where all organisms are potentially food and each organism feeds on more than one type of organism.

A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas (2012)

T he life sciences focus on patterns, processes, and relationships of living organisms. Life is self-contained, self-sustaining, self-replicating, and evolving, operating according to laws of the physical world, as well as genetic programming. Life scientists use observations, experiments, hypotheses, tests, models, theory, and technology to explore how life works. The study of life ranges over scales from single molecules, through organisms and ecosystems, to the entire biosphere, that is all life on Earth. It examines processes that occur on time scales from the blink of an eye to those that happen over billions of years. Living systems are interconnected and interacting. Although living organisms respond to the physical environment or geosphere, they have also fundamentally changed Earth over evolutionary time. Rapid advances in life sciences are helping to provide biological solutions to societal problems related to food, energy, health, and environment.

From viruses and bacteria to plants to fungi to animals, the diversity of the millions of life forms on Earth is astonishing. Without unifying principles, it would be difficult to make sense of the living world and apply those understandings to solving problems. A core principle of the life sciences is that all organisms are related by evolution and that evolutionary processes have led to the tremendous diversity of the biosphere. There is diversity within species as well as between species. Yet what is learned about the function of a gene or a cell or a process in one organism is relevant to other organisms because of their ecological interactions and evolutionary relatedness. Evolution and its underlying genetic

mechanisms of inheritance and variability are key to understanding both the unity and the diversity of life on Earth.

The committee developed four core ideas reflecting unifying principles in life sciences. These core ideas are essential for a conceptual understanding of the life sciences and will enable students to make sense of emerging research findings. We begin at the level of organisms, delving into the many processes and structures, at scales ranging from components as small as individual atoms to organ systems that are necessary for life to be sustained. Our focus then broadens to consider organisms in their environment&mdashhow they interact with the environment&rsquos living (biotic) and physical (abiotic) features. Next the chapter considers how organisms reproduce, passing genetic information to their offspring, and how these mechanisms lead to variability and hence diversity within species. Finally, the core ideas in the life sciences culminate with the principle that evolution can explain how the diversity that is observed within species has led to the diversity of life across species through a process of descent with adaptive modification. Evolution also accounts for the remarkable similarity of the fundamental characteristics of all species.

The first core idea, LS1: From Molecules to Organisms: Structures and Processes, addresses how individual organisms are configured and how these structures function to support life, growth, behavior, and reproduction. The first core idea hinges on the unifying principle that cells are the basic unit of life.

The second core idea, LS2: Ecosystems: Interactions, Energy, and Dynamics, explores organisms&rsquo interactions with each other and their physical environment. This includes how organisms obtain resources, how they change their environment, how changing environmental factors affect organisms and ecosystems, how social interactions and group behavior play out within and between species, and how these factors all combine to determine ecosystem functioning.

The third core idea, LS3: Heredity: Inheritance and Variation of Traits across generations, focuses on the flow of genetic information between generations. This idea explains the mechanisms of genetic inheritance and describes the environmental and genetic causes of gene mutation and the alteration of gene expression.

The fourth core idea, LS4: Biological Evolution: Unity and Diversity, explores &ldquochanges in the traits of populations of organisms over time&rdquo [1] and the factors that account for species&rsquo unity and diversity alike. The section

Evolution and its underlying genetic mechanisms of inheritance and variability are key to understanding both the unity and the diversity of life on Earth.

begins with a discussion of the converging evidence for shared ancestry that has emerged from a variety of sources (e.g., comparative anatomy and embryology, molecular biology and genetics). It describes how variation of genetically determined traits in a population may give some members a reproductive advantage in a given environment. This natural selection can lead to adaptation, that is, to a distribution of traits in the population that is matched to and can change with environmental conditions. Such adaptations can eventually lead to the development of separate species in separated populations. Finally, the idea describes the factors, including human activity, that affect biodiversity in an ecosystem, and the value of biodiversity in ecosystem resilience. See Box 6-1 for a summary of these four core ideas and their components.

These four core ideas, which represent basic life sciences fields of investigation&mdashstructures and processes in organisms, ecology, heredity, and evolution&mdashhave a long history and solid foundation based on the research evidence established by many scientists working across multiple fields. The role of unifying principles in advancing modern life sciences is articulated in The Role of Theory in Advancing 21st-Century Biology and A New Biology for the 21st Century [2, 3]. In developing these core ideas, the committee also drew on the established K-12 science education literature, including National Science Education Standards and Benchmarks for Science Literacy [4, 5]. The ideas also incorporate contemporary documents, such as the Science College Board Standards for College Success [6], and the ideas are consistent with frameworks for national and international assessments, such as those of the National Assessment of Educational Progress (NAEP), the Programme for International Student Assessment (PISA), and the Trends in International Mathematics and Science Study (TIMSS) [7-9]. Furthermore, the ideas align with the core concepts for biological literacy for undergraduates to build on as described in the American Association for the Advancement of Science (AAAS) report Vision and Change in Undergraduate Biology Education [10].


Core Idea LS1: From Molecules to Organisms: Structures and Processes

LS1.A: Structure and Function

LS1.B: Growth and Development of Organisms

LS1.C: Organization for Matter and Energy Flow in Organisms

LS1.D: Information Processing

Core Idea LS2: Ecosystems: Interactions, Energy, and Dynamics

LS2.A: Interdependent Relationships in Ecosystems

LS2.B: Cycles of Matter and Energy Transfer in Ecosystems

LS2.C: Ecosystem Dynamics, Functioning, and Resilience

LS2.D: Social Interactions and Group Behavior

Core Idea LS3: Heredity: Inheritance and Variation of Traits

LS3.A: Inheritance of Traits

Core Idea LS4: Biological Evolution: Unity and Diversity

LS4.A: Evidence of Common Ancestry and Diversity

LS4.D: Biodiversity and Humans

From Molecules to Organisms: Structures and Processes

How do organisms live, grow, respond to their environment, and reproduce?

All living organisms are made of cells. Life is the quality that distinguishes living things&mdashcomposed of living cells&mdashfrom nonliving objects or those that have died. While a simple definition of life can be difficult to capture, all living things&mdashthat is to say all organisms&mdashcan be characterized by common aspects of their structure and functioning. Organisms are complex, organized, and built on a hierarchical structure, with each level providing the foundation for the next, from the chemical foundation of elements and atoms, to the cells and systems of individual organisms, to species and populations living and interacting in complex ecosystems. Organisms can be made of a single cell or millions of cells working together and include animals, plants, algae, fungi, bacteria, and all other microorganisms.

Organisms respond to stimuli from their environment and actively maintain their internal environment through homeostasis. They grow and reproduce, transferring their genetic information to their offspring. While individual organisms carry the same genetic information over their lifetime, mutation and the transfer from parent to offspring produce new combinations of genes. Over generations natural selection can lead to changes in a species overall hence, species evolve over time. To maintain all of these processes and functions, organisms require materials and energy from their environment nearly all energy that sustains life ultimately comes from the sun.


How do the structures of organisms enable life&rsquos functions?

A central feature of life is that organisms grow, reproduce, and die. They have characteristic structures (anatomy and morphology), functions (molecular-scale processes to organism-level physiology), and behaviors (neurobiology and, for some animal species, psychology). Organisms and their parts are made of cells, which are the structural units of life and which themselves have molecular substructures that support their functioning. Organisms range in composition from a single cell (unicellular microorganisms) to multicellular organisms, in which different groups of large numbers of cells work together to form systems

of tissues and organs (e.g., circulatory, respiratory, nervous, musculoskeletal), that are specialized for particular functions.

Special structures within cells are also responsible for specific cellular functions. The essential functions of a cell involve chemical reactions between many types of molecules, including water, proteins, carbohydrates, lipids, and nucleic acids. All cells contain genetic information, in the form of DNA. Genes are specific regions within the extremely large DNA molecules that form the chromosomes. Genes contain the instructions that code for the formation of molecules called proteins, which carry out most of the work of cells to perform the essential functions of life. That is, proteins provide structural components, serve as signaling devices, regulate cell activities, and determine the performance of cells through their enzymatic actions.

Grade Band Endpoints for LS1.A

By the end of grade 2. All organisms have external parts. Different animals use their body parts in different ways to see, hear, grasp objects, protect themselves, move from place to place, and seek, find, and take in food, water and air. Plants also have different parts (roots, stems, leaves, flowers, fruits) that help them survive, grow, and produce more plants.

By the end of grade 5. Plants and animals have both internal and external structures that serve various functions in growth, survival, behavior, and reproduction. (Boundary: Stress at this grade level is on understanding the macroscale systems and their function, not microscopic processes.)

By the end of grade 8. All living things are made up of cells, which is the smallest unit that can be said to be alive. An organism may consist of one single cell (unicellular) or many different numbers and types of cells (multicellular). Unicellular organisms (microorganisms), like multicellular organisms, need food, water, a way to dispose of waste, and an environment in which they can live.

Within cells, special structures are responsible for particular functions, and the cell membrane forms the boundary that controls what enters and leaves the cell. In multicellular organisms, the body is a system of multiple interacting subsystems. These subsystems are groups of cells that work together to form tissues or organs that are specialized for particular body functions. (Boundary: At this grade level, only a few major cell structures should be introduced.)

By the end of grade 12. Systems of specialized cells within organisms help them perform the essential functions of life, which involve chemical reactions that take place between different types of molecules, such as water, proteins, carbohydrates, lipids, and nucleic acids. All cells contain genetic information in the form of DNA molecules. Genes are regions in the DNA that contain the instructions that code for the formation of proteins, which carry out most of the work of cells.

Multicellular organisms have a hierarchical structural organization, in which any one system is made up of numerous parts and is itself a component of the next level. Feedback mechanisms maintain a living system&rsquos internal conditions within certain limits and mediate behaviors, allowing it to remain alive and functional even as external conditions change within some range. Outside that range (e.g., at a too high or too low external temperature, with too little food or water available), the organism cannot survive. Feedback mechanisms can encourage (through positive feedback) or discourage (negative feedback) what is going on inside the living system.


How do organisms grow and develop?

The characteristic structures, functions, and behaviors of organisms change in predictable ways as they progress from birth to old age. For example, upon reaching adulthood, organisms can reproduce and transfer their genetic information to their offspring. Animals engage in behaviors that increase their chances for reproduction, and plants may develop specialized structures and/or depend on animal behavior to accomplish reproduction.

Understanding how a single cell can give rise to a complex, multicellular organism builds on the concepts of cell division and gene expression. In multi-cellular organisms, cell division is an essential component of growth, development, and repair. Cell division occurs via a process called mitosis: when a cell divides in two, it passes identical genetic material to two daughter cells. Successive divisions produce many cells. Although the genetic material in each of the cells is identical, small differences in the immediate environments activate or inactivate different genes, which can cause the cells to develop slightly differently. This process of differentiation allows the body to form specialized cells that perform diverse functions, even though they are all descended from a single cell, the fertilized egg. Cell growth and differentiation are the mechanisms by which a fertilized egg develops into a complex organism. In sexual reproduction, a specialized type of cell division

called meiosis occurs and results in the production of sex cells, such as gametes (sperm and eggs) or spores, which contain only one member from each chromosome pair in the parent cell.

Grade Band Endpoints for LS1.B

By the end of grade 2. Plants and animals have predictable characteristics at different stages of development. Plants and animals grow and change. Adult plants and animals can have young. In many kinds of animals, parents and the offspring themselves engage in behaviors that help the offspring to survive.

By the end of grade 5. Reproduction is essential to the continued existence of every kind of organism. Plants and animals have unique and diverse life cycles that include being born (sprouting in plants), growing, developing into adults, reproducing, and eventually dying.

By the end of grade 8. Organisms reproduce, either sexually or asexually, and transfer their genetic information to their offspring. Animals engage in characteristic behaviors that increase the odds of reproduction. Plants reproduce in a variety of ways, sometimes depending on animal behavior and specialized features (such as attractively colored flowers) for reproduction. Plant growth can continue throughout the plant&rsquos life through production of plant matter in photosynthesis. Genetic factors as well as local conditions affect the size of the adult plant. The growth of an animal is controlled by genetic factors, food intake, and interactions with other organisms, and each species has a typical adult size range. (Boundary: Reproduction is not treated in any detail here for more specifics about grade level, see LS3.A.)

By the end of grade 12. In multicellular organisms individual cells grow and then divide via a process called mitosis, thereby allowing the organism to grow. The organism begins as a single cell (fertilized egg) that divides successively to produce many cells, with each parent cell passing identical genetic material (two variants

of each chromosome pair) to both daughter cells. As successive subdivisions of an embryo&rsquos cells occur, programmed genetic instructions and small differences in their immediate environments activate or inactivate different genes, which cause the cells to develop differently&mdasha process called differentiation. Cellular division and differentiation produce and maintain a complex organism, composed of systems of tissues and organs that work together to meet the needs of the whole organism. In sexual reproduction, a specialized type of cell division called meiosis occurs that results in the production of sex cells, such as gametes in animals (sperm and eggs), which contain only one member from each chromosome pair in the parent cell.


How do organisms obtain and use the matter and energy they need to live and grow?

Sustaining life requires substantial energy and matter inputs. The complex structural organization of organisms accommodates the capture, transformation, transport, release, and elimination of the matter and energy needed to sustain them. As matter and energy flow through different organizational levels&mdashcells, tissues, organs, organisms, populations, communities, and ecosystems&mdashof living systems, chemical elements are recombined in different ways to form different products. The result of these chemical reactions is that energy is transferred from one system of interacting molecules to another.

In most cases, the energy needed for life is ultimately derived from the sun through photosynthesis (although in some ecologically important cases, energy is derived from reactions involving inorganic chemicals in the absence of sunlight&mdashe.g., chemosynthesis). Plants, algae (including phytoplankton), and other energy-fixing microorganisms use sunlight, water, and carbon dioxide to facilitate photosynthesis, which stores energy, forms plant matter, releases oxygen, and maintains plants&rsquo activities. Plants and algae&mdashbeing the resource base for animals, the animals that feed on animals, and the decomposers&mdashare energy-fixing organisms that sustain the rest of the food web.

Grade Band Endpoints for LS1.C

By the end of grade 2. All animals need food in order to live and grow. They obtain their food from plants or from other animals. Plants need water and light to live and grow.

By the end of grade 5. Animals and plants alike generally need to take in air and water, animals must take in food, and plants need light and minerals anaerobic life, such as bacteria in the gut, functions without air. Food provides animals with the materials they need for body repair and growth and is digested to release the energy they need to maintain body warmth and for motion. Plants acquire their material for growth chiefly from air and water and process matter they have formed to maintain their internal conditions (e.g., at night).

By the end of grade 8. Plants, algae (including phytoplankton), and many microorganisms use the energy from light to make sugars (food) from carbon dioxide from the atmosphere and water through the process of photosynthesis, which also releases oxygen. These sugars can be used immediately or stored for growth or later use. Animals obtain food from eating plants or eating other animals. Within individual organisms, food moves through a series of chemical reactions in which it is broken down and rearranged to form new molecules, to support growth, or to release energy. In most animals and plants, oxygen reacts with carbon-containing molecules (sugars) to provide energy and produce carbon dioxide anaerobic bacteria achieve their energy needs in other chemical processes that do not require oxygen.

By the end of grade 12. The process of photosynthesis converts light energy to stored chemical energy by converting carbon dioxide plus water into sugars plus released oxygen. The sugar molecules thus formed contain carbon, hydrogen, and oxygen their hydrocarbon backbones are used to make amino acids and other carbon-based molecules that can be assembled into larger molecules (such as proteins or DNA), used for example to form new cells. As matter and energy flow through different organizational levels of living systems, chemical elements are recombined in different ways to form different products. As a result of these chemical reactions, energy is transferred from one system of interacting molecules to another. For example, aerobic (in the presence of oxygen) cellular respiration is a chemical process in which the bonds of food molecules and oxygen molecules are broken and new compounds are formed that can transport energy to muscles. Anaerobic (without oxygen) cellular respiration follows a different and less efficient chemical pathway to provide energy in cells. Cellular respiration also releases the energy needed to maintain body temperature despite ongoing energy loss to the surrounding environment. Matter and energy are conserved in each change. This is true of all biological systems, from individual cells to ecosystems.


How do organisms detect, process, and use information about the environment?

An organism&rsquos ability to sense and respond to its environment enhances its chance of surviving and reproducing. Animals have external and internal sensory receptors that detect different kinds of information, and they use internal mechanisms for processing and storing it. Each receptor can respond to different inputs (electromagnetic, mechanical, chemical), some receptors respond by transmitting impulses that travel along nerve cells. In complex organisms, most such inputs travel to the brain, which is divided into several distinct regions and circuits that serve primary roles, in particular functions such as visual perception, auditory perception, interpretation of perceptual information, guidance of motor movement, and decision making. In addition, some of the brain&rsquos circuits give rise to emotions and store memories. Brain function also involves multiple interactions between the various regions to form an integrated sense of self and the surrounding world.

Grade Band Endpoints for LS1.D

By the end of grade 2. Animals have body parts that capture and convey different kinds of information needed for growth and survival&mdashfor example, eyes for light, ears for sounds, and skin for temperature or touch. Animals respond to these inputs with behaviors that help them survive (e.g., find food, run from a predator). Plants also respond to some external inputs (e.g., turn leaves toward the sun).

By the end of grade 5. Different sense receptors are specialized for particular kinds of information, which may then be processed and integrated by an animal&rsquos brain, with some information stored as memories. Animals are able to use their perceptions and memories to guide their actions. Some responses to information are instinctive&mdashthat is, animals&rsquo brains are organized so that they do not have to think about how to respond to certain stimuli.

By the end of grade 8. Each sense receptor responds to different inputs (electromagnetic, mechanical, chemical), transmitting them as signals that travel along nerve cells to the brain. The signals are then processed in the brain, resulting in immediate behaviors or memories. Changes in the structure and functioning of many millions of interconnected nerve cells allow combined inputs to be stored as memories for long periods of time.

By the end of grade 12. In complex animals, the brain is divided into several distinct regions and circuits, each of which primarily serves dedicated functions, such as visual perception, auditory perception, interpretation of perceptual information, guidance of motor movement, and decision making about actions to take in the event of certain inputs. In addition, some circuits give rise to emotions and memories that motivate organisms to seek rewards, avoid punishments, develop fears, or form attachments to members of their own species and, in some cases, to individuals of other species (e.g., mixed herds of mammals, mixed flocks of birds). The integrated functioning of all parts of the brain is important for successful interpretation of inputs and generation of behaviors in response to them.

Ecosystems: Interactions, Energy, and Dynamics

How and why do organisms interact with their environment and what are the effects of these interactions?

Ecosystems are complex, interactive systems that include both biological communities (biotic) and physical (abiotic) components of the environment. As with individual organisms, a hierarchal structure exists groups of the same organisms (species) form populations, different populations interact to form communities, communities live within an ecosystem, and all of the ecosystems on Earth make up the biosphere. Organisms grow, reproduce, and perpetuate their species by obtaining necessary resources through interdependent relationships with other organisms and the physical environment. These same interactions can facilitate or restrain growth and enhance or limit the size of populations, maintaining the balance between available resources and those who consume them. These interactions can also change both biotic and abiotic characteristics of the environment. Like individual organisms, ecosystems are sustained by the continuous flow of energy, originating primarily from the sun, and the recycling of matter and nutrients within the system. Ecosystems are dynamic, experiencing shifts in population composition and abundance and changes in the physical environment over time, which ultimately affects the stability and resilience of the entire system.


How do organisms interact with the living and nonliving environments to obtain matter and energy?

Ecosystems are ever changing because of the interdependence of organisms of the same or different species and the nonliving (physical) elements of the environment. Seeking matter and energy resources to sustain life, organisms in an ecosystem interact with one another in complex feeding hierarchies of producers, consumers, and decomposers, which together represent a food web. Interactions between organisms may be predatory, competitive, or mutually beneficial. Ecosystems have carrying capacities that limit the number of organisms (within populations) they can support. Individual survival and population sizes depend on such factors as predation, disease, availability of resources, and parameters of the physical environment. Organisms rely on physical factors, such as light, temperature, water, soil, and space for shelter and reproduction. Earth&rsquos varied combinations of these factors provide the physical environments in which its ecosystems (e.g., deserts, grasslands, rain forests, and coral reefs) develop and in which the diverse species of the planet live. Within any one ecosystem, the biotic interactions between organisms (e.g., competition, predation, and various types of facilitation, such as pollination) further influence their growth, survival, and reproduction, both individually and in terms of their populations.

Grade Band Endpoints for LS2.A

By the end of grade 2. Animals depend on their surroundings to get what they need, including food, water, shelter, and a favorable temperature. Animals depend on plants or other animals for food. They use their senses to find food and water, and they use their body parts to gather, catch, eat, and chew the food. Plants depend on air, water, minerals (in the soil), and light to grow. Animals can move around, but plants cannot, and they often depend on animals for pollination or to move their seeds around. Different plants survive better in different settings because they have varied needs for water, minerals, and sunlight.

By the end of grade 5. The food of almost any kind of animal can be traced back to plants. Organisms are related in food webs in which some animals eat plants

for food and other animals eat the animals that eat plants. Either way, they are &ldquoconsumers.&rdquo Some organisms, such as fungi and bacteria, break down dead organisms (both plants or plants parts and animals) and therefore operate as &ldquodecomposers.&rdquo Decomposition eventually restores (recycles) some materials back to the soil for plants to use. Organisms can survive only in environments in which their particular needs are met. A healthy ecosystem is one in which multiple species of different types are each able to meet their needs in a relatively stable web of life. Newly introduced species can damage the balance of an ecosystem.

By the end of grade 8. Organisms and populations of organisms are dependent on their environmental interactions both with other living things and with nonliving factors. Growth of organisms and population increases are limited by access to resources. In any ecosystem, organisms and populations with similar requirements for food, water, oxygen, or other resources may compete with each other for limited resources, access to which consequently constrains their growth and reproduction. Similarly, predatory interactions may reduce the number of organisms or eliminate whole populations of organisms. Mutually beneficial interactions, in contrast, may become so interdependent that each organism requires the other for survival. Although the species involved in these competitive, predatory, and mutually beneficial interactions vary across ecosystems, the patterns of interactions of organisms with their environments, both living and nonliving, are shared.

By the end of grade 12. Ecosystems have carrying capacities, which are limits to the numbers of organisms and populations they can support. These limits result from such factors as the availability of living and nonliving resources and from such challenges as predation, competition, and disease. Organisms would have the capacity to produce populations of great size were it not for the fact that environments and resources are finite. This fundamental tension affects the abundance (number of individuals) of species in any given ecosystem.


How do matter and energy move through an ecosystem?

The cycling of matter and the flow of energy within ecosystems occur through interactions among different organisms and between organisms and the physical environment. All living systems need matter and energy. Matter fuels the energy-releasing chemical reactions that provide energy for life functions and provides the

material for growth and repair of tissue. Energy from light is needed for plants because the chemical reaction that produces plant matter from air and water requires an energy input to occur. Animals acquire matter from food, that is, from plants or other animals. The chemical elements that make up the molecules of organisms pass through food webs and the environment and are combined and recombined in different ways. At each level in a food web, some matter provides energy for life functions, some is stored in newly made structures, and much is discarded to the surrounding environment. Only a small fraction of the matter consumed at one level is captured by the next level up. As matter cycles and energy flows through living systems and between living systems and the physical environment, matter and energy are conserved in each change.

The carbon cycle provides an example of matter cycling and energy flow in ecosystems. Photosynthesis, digestion of plant matter, respiration, and decomposition are important components of the carbon cycle, in which carbon is exchanged between the biosphere, atmosphere, oceans, and geosphere through chemical, physical, geological, and biological processes.

Grade Band Endpoints for LS2.B

By the end of grade 2. Organisms obtain the materials they need to grow and survive from the environment. Many of these materials come from organisms and are used again by other organisms.

By the end of grade 5. Matter cycles between the air and soil and among plants, animals, and microbes as these organisms live and die. Organisms obtain gases, water, and minerals from the environment and release waste matter (gas, liquid, or solid) back into the environment.

By the end of grade 8. Food webs are models that demonstrate how matter and energy is transferred between producers (generally plants and other organisms that engage in photosynthesis), consumers, and decomposers as the three groups interact&mdashprimarily for food&mdashwithin an ecosystem. Transfers of matter into and out of the physical environment occur at every level&mdashfor example, when molecules from food react with oxygen captured from the environment, the carbon dioxide and water thus produced are transferred back to the environment, and ultimately so are waste products, such as fecal material. Decomposers recycle nutrients from dead plant or animal matter back to the soil in terrestrial environments or to the water in aquatic environments. The atoms that make up the

Ecosystems are sustained by the continuous flow of energy, originating primarily from the sun, and the recycling of matter and nutrients within the system.

organisms in an ecosystem are cycled repeatedly between the living and nonliving parts of the ecosystem.

By the end of grade 12. Photosynthesis and cellular respiration (including anaerobic processes) provide most of the energy for life processes. Plants or algae form the lowest level of the food web. At each link upward in a food web, only a small fraction of the matter consumed at the lower level is transferred upward, to produce growth and release energy in cellular respiration at the higher level. Given this inefficiency, there are generally fewer organisms at higher levels of a food web, and there is a limit to the number of organisms that an ecosystem can sustain.

The chemical elements that make up the molecules of organisms pass through food webs and into and out of the atmosphere and soil and are combined and recombined in different ways. At each link in an ecosystem, matter and energy are conserved some matter reacts to release energy for life functions, some matter is stored in newly made structures, and much is discarded. Competition among species is ultimately competition for the matter and energy needed for life.

Photosynthesis and cellular respiration are important components of the carbon cycle, in which carbon is exchanged between the biosphere, atmosphere, oceans, and geosphere through chemical, physical, geological, and biological processes.


What happens to ecosystems when the environment changes?

Ecosystems are dynamic in nature their characteristics fluctuate over time, depending on changes in the environment and in the populations of various species. Disruptions in the physical and biological components of an ecosystem&mdashwhich can lead to shifts in the types and numbers of the ecosystem&rsquos organisms, to the maintenance or the extinction of species, to the migration of species into or out of the region, or to the formation of new species (speciation)&mdashoccur for a

variety of natural reasons. Changes may derive from the fall of canopy trees in a forest, for example, or from cataclysmic events, such as volcanic eruptions. But many changes are induced by human activity, such as resource extraction, adverse land use patterns, pollution, introduction of nonnative species, and global climate change. Extinction of species or evolution of new species may occur in response to significant ecosystem disruptions.

Species in an environment develop behavioral and physiological patterns that facilitate their survival under the prevailing conditions, but these patterns may be maladapted when conditions change or new species are introduced. Ecosystems with a wide variety of species&mdashthat is, greater biodiversity&mdashtend to be more resilient to change than those with few species.

Grade Band Endpoints for LS2.C

By the end of grade 2. The places where plants and animals live often change, sometimes slowly and sometimes rapidly. When animals and plants get too hot or too cold, they may die. If they cannot find enough food, water, or air, they may die.

By the end of grade 5. When the environment changes in ways that affect a place&rsquos physical characteristics, temperature, or availability of resources, some organisms survive and reproduce, others move to new locations, yet others move into the transformed environment, and some die.

By the end of grade 8. Ecosystems are dynamic in nature their characteristics can vary over time. Disruptions to any physical or biological component of an ecosystem can lead to shifts in all of its populations.

Biodiversity describes the variety of species found in Earth&rsquos terrestrial and oceanic ecosystems. The completeness or integrity of an ecosystem&rsquos biodiversity is often used as a measure of its health.

Watch the video: Interdependence of Living Things (January 2022).