Trace Matter and Energy - Middle School Life Science

Which trophic level contains organisms that make their own food?

Producers (first trophic level). Only producers can convert inorganic matter into organic food.
What is the primary source of energy for most ecosystems on Earth?

Sunlight (solar energy). Powers photosynthesis, starting the energy flow through all food chains.
Which type of organism is a consumer, and where does its energy come from?

Heterotroph; eating other organisms. Must consume other organisms to obtain energy and matter.
Which molecule is the main usable energy currency of cells?

ATP. Adenosine triphosphate powers cellular processes.
Which evidence best shows that plant matter becomes animal mass after feeding?

Increase in consumer biomass after eating producers. Mass gain proves matter transfers from food to body.
What is the correct term for organisms that make their own food from inorganic sources?

Producers (autotrophs). Make organic molecules from $CO_2$ and water using energy.
Identify the correct direction of arrows in a food chain: from predator to prey or prey to predator?

From prey to predator (direction of energy transfer). Arrows show energy flow from eaten to eater.
What cell organelle is the main site of photosynthesis in plant cells?

Chloroplast. Contains chlorophyll and enzymes needed for photosynthesis.
Identify the form of energy stored in the bonds of glucose made by plants.

Chemical energy. Bonds between atoms store energy that cells can release.
Which organelles perform photosynthesis and cellular respiration in eukaryotes?

Chloroplasts; mitochondria. Chloroplasts capture light; mitochondria release energy from glucose.
In a food chain Grass → Rabbit → Fox, which organism is the primary consumer?

Rabbit. Eats producers (grass) directly; first consumer level.
What are the reactants of photosynthesis?

Carbon dioxide and water (plus light energy). These combine using light energy to form glucose and oxygen.
Identify the direction of arrows in a food chain: from eater to food or from food to eater?

From food (energy source) to eater (consumer). Shows energy flow direction from source to consumer.
Which option best traces energy in a food chain: Sun → plant → rabbit → fox or plant → Sun → rabbit → fox?

Sun → plant → rabbit → fox. Energy flows from sun through producers to consumers.
In an energy pyramid, which trophic level contains the most energy?

Producers (first trophic level). Energy decreases at each level due to heat loss.
What process do producers use to convert light energy into chemical energy in glucose?

Photosynthesis. Converts light energy and $CO_2$ into glucose molecules.
What is the term for organisms that must obtain energy by eating other organisms?

Heterotrophs (consumers). Must consume other organisms for energy and carbon.
What process do producers use to convert light energy into chemical energy stored in glucose?

Photosynthesis. Converts light energy into chemical bonds in glucose molecules.
If a plant's mass increases as it grows, which input provides most of the added atoms?

Carbon dioxide from the air. Plants convert $CO_2$ into biomass during photosynthesis.
Which statement best describes matter in ecosystems: cycles or flows one-way?

Matter cycles (atoms are conserved). Atoms are reused; carbon, nitrogen cycle through organisms repeatedly.
Which term names organisms that make their own food from inorganic materials?

Producers (autotrophs). Self-feeders that convert inorganic matter to organic food.
Which direction do arrows point in a food chain: toward the eater or toward the eaten?

Toward the eater (direction of energy transfer). Shows energy flow from eaten to eater.
In ecosystems, does energy cycle or flow in one direction?

Energy flows in one direction and is lost as heat. Cannot be recycled; eventually all energy becomes unusable heat.
What is the process by which plants convert light energy into chemical energy in glucose?

Photosynthesis. Plants capture light energy and store it in glucose molecules.
What is the correct term for organisms that obtain energy by eating other organisms?

Consumers (heterotrophs). Must eat other organisms because they can't make food.
If a plant contains carbon atoms, which molecule supplied most of that carbon?

Carbon dioxide ( $CO_2$ ) from the air. Plants absorb $CO_2$ during photosynthesis to build glucose.
Which type of organism makes its own food from inorganic materials: autotroph or heterotroph?

Autotroph. Self-feeders produce their own food through photosynthesis.
What happens to energy as it moves through trophic levels: does it recycle or flow and dissipate as heat?

It flows and much dissipates as heat. Energy cannot be recycled; it's lost as heat at each level.
What is the role of a consumer in an ecosystem?

Gets energy and matter by eating other organisms. Heterotrophs depend on other organisms for energy.
What are the products of cellular respiration?

Carbon dioxide, water, and usable energy (ATP). ATP powers cell activities; $CO_2$ and $H_2O$ are waste.
What process do plants use to convert light energy into chemical energy stored in sugar?

Photosynthesis. Converts light energy into glucose using $CO_2$ and water.
What happens to matter when an organism grows: is matter created, destroyed, or rearranged into biomass?

Rearranged into biomass (matter is conserved). Atoms from food become part of the organism's body.
What is the key difference between how matter and energy move through ecosystems?

Matter cycles; energy flows one-way and is lost as heat. Matter recycles between organisms; energy cannot be recycled.
Which statement is evidence that plants increase biomass by taking in matter from the air?

Plants take in $CO_2$ and build sugars and tissues. Carbon from air becomes plant mass through photosynthesis.
What is the main process plants use to convert light energy into stored chemical energy?

Photosynthesis. Converts $CO_2$ and water into glucose using light.
Which statement best describes how energy moves through an ecosystem?

Energy flows one-way and is lost as heat at each transfer. Energy cannot be recycled, unlike matter.
Which evidence best shows that plant mass comes mostly from air rather than soil?

Plants use $CO_2$ to build sugars and biomass. Carbon from air becomes plant mass through photosynthesis.
Identify the trophic role of rabbit in the chain grass → rabbit → fox.

Primary consumer. Eats producers (herbivore) directly.
Choose the best evidence that matter is conserved in organisms: mass gain from food, or energy loss as heat?

Mass gain from food (atoms rearranged into body molecules). Food atoms become body structures, conserving matter.
What is the immediate energy-carrying molecule used by cells for most activities?

ATP. Universal energy currency that powers cellular work.
What process do most organisms use to transfer energy from glucose to ATP?

Cellular respiration. Breaks down glucose to release energy stored in chemical bonds.
What does ATP represent in cells when tracing energy through organisms?

Usable chemical energy for cell work. ATP stores energy from food in a form cells can use immediately.
What process in producers converts light energy into chemical energy stored in glucose?

Photosynthesis. Converts light energy to chemical bonds in sugar molecules.
What term describes organisms that must obtain energy by eating other organisms?

Consumers (heterotrophs). Cannot make their own food, so must eat other organisms.
What is a food chain?

A single pathway of energy transfer by eating and being eaten. Linear sequence showing who eats whom.
What process do producers use to convert light energy into chemical energy in sugars?

Photosynthesis. Converts light energy into chemical energy stored in glucose.
What is the definition of a producer in an ecosystem?

An organism that makes its own food (usually by photosynthesis). Forms the base of food chains by converting light to chemical energy.
What is the role of decomposers in tracing matter through an ecosystem?

Break down dead matter and recycle nutrients. They return atoms from dead organisms to soil and atmosphere.
What happens to most energy at each trophic level transfer?

It is used for life processes and released as heat. Only ~10% transfers to next level; 90% lost.
Choose the best evidence that decomposers recycle matter: they convert dead organisms into ____.

Nutrients (simpler substances) returned to soil and water. Breaking down releases minerals for producer uptake.
What process in cells releases usable energy by breaking down glucose with oxygen?

Cellular respiration. Breaks chemical bonds to release ATP for cell work.
Which process converts light energy into chemical energy stored in glucose?

Photosynthesis. Plants use chlorophyll to capture light and make glucose.
Identify the trophic level of fox in the chain: grass → rabbit → fox.

Secondary consumer. Third trophic level; eats primary consumers.
What is the correct term for organisms that break down dead matter and wastes into simpler substances?

Decomposers. Recycle nutrients by breaking down organic matter.
What happens to most energy at each trophic level as it moves through a food web?

It is released as heat and used for life processes. Only ~10% transfers up; rest lost as heat during metabolism.
Which molecules are products of cellular respiration?

Carbon dioxide, water, and usable energy (ATP). Breaking glucose bonds releases energy and waste products.
Identify the trophic role of fox in the chain grass → rabbit → fox.

Secondary consumer. Eats primary consumers (carnivore).
Choose the correct direction of energy flow in a food chain.

Producer → consumer(s) → decomposer. Energy flows from organisms that make food to those that eat it.
Which option best traces matter: carbon atoms in CO₂ become part of what in a plant?

Glucose and other organic molecules in plant tissues. Carbon atoms become part of sugar molecules during photosynthesis.
What term describes an organism that makes its own food from inorganic materials?

Producer (autotroph). Uses photosynthesis or chemosynthesis to make organic molecules.
What is the correct word for an organism that makes its own food from inorganic materials?

Autotroph (producer). Self-feeders that produce organic molecules from inorganic sources.
What is a trophic level?

A feeding position in a food chain or food web. Each level represents organisms with similar energy sources.
Which statement best describes how matter moves through an ecosystem?

Matter is recycled through organisms and the environment. Atoms are rearranged but never created or destroyed.
Identify the missing trophic role: grass → rabbit → fox; the rabbit is a(n) ____.

Primary consumer (herbivore). Eats producers (grass) and is eaten by secondary consumers.
What is ATP primarily used for in cells?

Immediate energy for cellular work. ATP provides ready-to-use energy for all cell processes.
What is the correct term for an organism that makes its own food using sunlight?

Producer (autotroph). Uses photosynthesis to convert light into chemical energy.
Identify the trophic level of fox in the chain: grass → rabbit → fox.

Secondary consumer. Carnivore that eats primary consumers.
Identify the main source of atoms in a carnivore's body mass: sunlight, minerals, or the prey it eats?

The prey it eats (matter transferred through feeding). Carnivores incorporate atoms from prey tissues into their own bodies.
What is the correct term for organisms that break down dead matter and recycle nutrients?

Decomposers. Return nutrients to soil by breaking down dead organisms.
Which gas is taken in by plants during photosynthesis?

Carbon dioxide ( $CO_2$ ). Raw material combined with water to make glucose.
What is the main cellular process that releases usable energy (ATP) from glucose?

Cellular respiration. Breaks down glucose to produce ATP for cellular work.
What are the main products of photosynthesis?

Glucose and $O_2$ . Sugar stores energy; oxygen is released as byproduct.
What is the term for many interconnected food chains in an ecosystem?

Food web. Shows complex feeding relationships in ecosystems.
Which statement best describes how matter moves through ecosystems?

Matter is conserved and cycles through organisms and the environment. Atoms recycle between living things and environment repeatedly.
Identify the main form of energy stored in food molecules made by producers.

Chemical energy in bonds (for example, in glucose). Photosynthesis stores solar energy in glucose's chemical bonds.
Which statement is evidence that decomposers return matter to the environment?

Nutrients increase in soil as dead organisms break down. Decomposition releases minerals back to soil.
Which option best traces matter in a food chain: atoms move into biomass, or energy turns into matter?

Atoms move into biomass (energy does not become matter). Matter is conserved; energy and matter are different.
Which direction do arrows point in a food chain: toward the eater or toward the eaten?

Toward the eater (direction of energy transfer). Shows energy flow from eaten organism to eater.
Which type of organism is a producer (autotroph) in a food web?

An organism that makes its own food (for example, plants). Producers convert light energy into food molecules.
What is the main function of cellular respiration in cells?

Convert food energy into usable ATP. Breaks down glucose to release energy for cellular work.
What is the role of decomposers in tracing matter through ecosystems?

They break down dead matter and recycle nutrients. Return nutrients to soil for producers to reuse.
What cell organelle releases usable energy by breaking down glucose during cellular respiration?

Mitochondrion. Site where glucose is broken down to produce ATP.
What is a decomposer, and what does it do to matter in dead organisms?

A recycler that breaks down dead matter into simpler substances. Returns nutrients to soil for producer uptake.
Which term names organisms that must obtain food by eating other organisms?

Consumers (heterotrophs). Other-feeders that depend on organic matter from organisms.
What process do producers use to convert light energy into chemical energy in glucose?

Photosynthesis. Converts light energy to chemical bonds in glucose molecules.
Which process returns carbon dioxide to the atmosphere from organisms?

Cellular respiration. Organisms break down glucose, releasing CO₂ as waste.
What are the products of cellular respiration?

Carbon dioxide, water, and ATP (usable energy). ATP powers cell activities; $CO_2$ and water are waste products.
Which statement is correct: matter cycles in ecosystems, or matter is destroyed in ecosystems?

Matter cycles in ecosystems. Atoms are reused; matter is never created or destroyed.
Which statement best describes matter in ecosystems: cycles or flows one-way?

Matter cycles through organisms and the environment. Atoms are reused, not created or destroyed.
Which type of organism gets energy by consuming other organisms: autotroph or heterotroph?

Heterotroph. Must eat other organisms because they cannot make their own food.
What is a decomposer, and what is its role in tracing matter through ecosystems?

Organism that breaks down dead matter and recycles nutrients. Returns nutrients to soil for producers to reuse.
If an animal exhales $CO_2$ , which process is the direct source of that $CO_2$ ?

Cellular respiration. Breaks down organic molecules, releasing $CO_2$ as waste.
What process transfers energy from sunlight into chemical energy in glucose?

Photosynthesis. Converts light energy into chemical bonds in glucose molecules.
What molecule is the immediate usable energy currency of cells?

ATP. Energy molecule that powers cellular processes like movement and growth.
Identify the trophic role of grass in the chain grass → rabbit → fox.

Producer. Makes its own food through photosynthesis.
What is the term for a feeding relationship sequence showing energy transfer?

Food chain. Linear path showing who eats whom in an ecosystem.
What are the main reactants of photosynthesis?

$CO_2$ and $H_2O$ (with light energy). Starting materials that combine to form glucose.
Which statement best traces matter: 'energy is recycled' or 'atoms are rearranged'?

Atoms are rearranged. Matter is conserved; atoms just form new molecules.
Choose the best evidence that plant mass mostly comes from air rather than soil: mass gain with little soil loss?

Large plant mass gain with minimal soil mass decrease. Plants gain kilograms while soil loses only grams, proving air is source.
What process do organisms use to release energy from glucose for cell work?

Cellular respiration. Breaks down glucose with oxygen to produce ATP for cell activities.
Identify the correct tracing statement: energy in a plant is stored mainly as ____ matter.

Chemical energy in sugars (biomass). Photosynthesis stores energy as glucose and other organic molecules.
What is the best evidence that matter is conserved when organisms grow?

Atoms are rearranged into new molecules; none are created or destroyed. Conservation of mass means atoms persist through reactions.
What is the main energy source for most ecosystems that powers food webs?

Sunlight (solar energy). Captures light energy that drives all other energy transfers.
What is the definition of a decomposer in an ecosystem?

An organism that breaks down dead matter and recycles nutrients. Essential for returning nutrients to soil for producer use.
In matter and energy terms, what happens to energy as it moves up trophic levels?

It decreases; much is lost as heat. Only ~10% transfers up; rest lost to metabolism/heat.
What is the role of a producer in an ecosystem?

Makes its own food from sunlight or chemicals. Autotrophs form the base of food chains.
Which gas is released during cellular respiration and can be measured as evidence of energy release from food?

CO $_2$ . Waste product shows glucose is being broken down for energy.
Which trophic level has the most available energy: producers or tertiary consumers?

Producers. First to capture energy; each level up loses ~90%.
What is the process called when cells break down glucose to release usable energy?

Cellular respiration. Breaks chemical bonds in glucose to release ATP for cell work.
What molecule provides most of the carbon atoms that end up in a plant's biomass?

Carbon dioxide ( $CO_2$ ) from the air. Photosynthesis fixes atmospheric carbon into organic molecules.
Identify where matter goes when a consumer uses food for growth and repair.

Into the consumer's body tissues (biomass). Food molecules become part of the consumer's cells and tissues.
In ecosystems, does matter cycle or flow in one direction?

Matter cycles. Atoms are reused; carbon, nitrogen cycle through ecosystems repeatedly.
What is the main energy-storing molecule made by photosynthesis and used in cellular respiration?

Glucose. A sugar molecule that stores chemical energy from photosynthesis.
Which option best describes a food web compared with a food chain?

A network of interconnected feeding relationships. Shows multiple pathways, unlike a single linear chain.
What form of energy is transferred from organism to organism when one eats another?

Chemical energy stored in food molecules. Bonds in organic molecules store energy from photosynthesis.
Which option best traces matter in a carnivore: does it come from sunlight or from eaten organisms?

From eaten organisms (food becomes body matter). Matter transfers through food chains, not directly from sun.
Which statement is correct: matter cycles or energy cycles through ecosystems?

Matter cycles; energy flows one-way. Atoms recycle but energy dissipates as heat, requiring constant input.
What are the reactants of photosynthesis?

Carbon dioxide and water (with light energy). Plants absorb these simple molecules to build complex sugars.
What is the primary source of energy for nearly all food webs on Earth?

Sunlight (solar energy). Producers capture this energy to start all food chains.
What is the process called when producers convert light energy into chemical energy?

Photosynthesis. Converts light energy into chemical energy stored in glucose molecules.
What is a trophic level?

A feeding position in a food chain or food web. Each level represents organisms with similar energy sources.
Which type of organism is a producer in a food chain?

An autotroph (for example, a plant or algae). Makes its own food from inorganic materials using energy.
What is the process called when producers convert light energy into chemical energy (glucose)?

Photosynthesis. Converts light energy to chemical energy stored in glucose.
Identify the direction of arrows in a food web: toward the eater or toward the organism being eaten?

Toward the eater (energy moves to the consumer). Arrows show energy flowing from prey to predator.
Which statement best describes energy in ecosystems: cycles or flows one-way?

Energy flows one-way and is lost as heat. Cannot be recycled; constantly needs new solar input.
Which statement best describes how matter moves in ecosystems: cycles or flows?

Matter cycles through ecosystems. Atoms are reused; carbon cycles between organisms and air.
Which statement is correct: matter cycles in ecosystems or energy cycles in ecosystems?

Matter cycles; energy flows one way. Energy enters as sunlight and exits as heat; matter recycles.
What is the chemical equation for cellular respiration (reactants and products)?

$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$ . Shows glucose and oxygen breaking down to release energy as ATP.
What term describes organisms that break down dead organisms and wastes into simpler substances?

Decomposers. Recycle nutrients by breaking down organic matter to inorganic forms.
If a plant gains 2 kg of mass, which molecule supplied most of the carbon atoms?

$CO_2$ from the air. Plants fix atmospheric carbon into organic molecules.
Which statement best describes energy flow in ecosystems: cycle or one-way?

One-way flow (eventually lost as heat). Energy cannot be recycled; it's lost as heat at each transfer.
Identify the evidence that plant mass mainly comes from air rather than soil.

Plants take in $CO_2$ and build it into sugars and tissues. Carbon from air becomes plant mass through photosynthesis.
What is the main source of energy for most food webs on Earth?

Sunlight (solar energy). Captured by producers through photosynthesis to start food chains.
Which level is the primary consumer in this chain: grass → rabbit → fox?

Rabbit. First consumer that eats the producer (grass).
Which graph trend best supports energy loss between trophic levels in a pyramid?

Energy decreases at each higher trophic level. Only ~10% transfers up; rest lost as heat/waste.
Which type of organism makes its own food from inorganic materials using energy?

Producer (autotroph). Uses photosynthesis or chemosynthesis to produce organic compounds.
Which gas is released by plants as a product of photosynthesis?

Oxygen ( $O_2$ ). Byproduct when water molecules are split for electrons.
What process do cells use to release usable energy from glucose?

Cellular respiration. Breaks down glucose to release ATP for cellular work.
What is the chemical equation for photosynthesis (reactants and products)?

$6CO_2 + 6H_2O + \text{light} \rightarrow C_6H_{12}O_6 + 6O_2$ . Shows carbon dioxide and water becoming glucose and oxygen using light.
What is the main evidence that energy is lost from ecosystems at each transfer?

Heat is produced during metabolism and respiration. Organisms generate heat maintaining body temperature and moving.
Identify the trophic level of rabbit in the chain: grass → rabbit → fox.

Primary consumer. Second trophic level; eats producers directly.
What process do producers use to convert light energy into chemical energy in sugars?

Photosynthesis. Converts light energy and CO₂ into glucose using chlorophyll.
What is the primary source of energy for most food webs on Earth?

Sunlight (solar energy). Producers capture this energy to start all food chains.
Which statement best traces carbon atoms after a deer eats plants and respires?

Some carbon becomes deer biomass; some leaves as $\text{CO}_2$ . Carbon atoms split between growth and respiration waste.
Which trophic level directly consumes producers: primary, secondary, or tertiary consumers?

Primary consumers. Herbivores that eat plants directly.
Which statement best describes matter in ecosystems: recycled or used up?

Matter is recycled through biogeochemical cycles. Atoms are rearranged but never created or destroyed.
Which type of organism must obtain matter and energy by eating other organisms?

Consumer (heterotroph). Cannot produce own food; depends on consuming other organisms.
Which direction does carbon matter move when a fox eats a rabbit: rabbit → fox or fox → rabbit?

Rabbit → fox. Matter transfers from prey to predator when eaten.
What is the best definition of a trophic level?

An organism's feeding position in a food chain or web. Each level represents who eats whom in the ecosystem.
Which process moves nitrogen from the air into usable forms for plants?

Nitrogen fixation by bacteria. Converts atmospheric N₂ into ammonia plants can absorb.
Which type of organism is a consumer (heterotroph) in a food web?

An organism that gets energy by eating other organisms. Consumers must eat to obtain energy and matter.
Which process returns carbon dioxide to the atmosphere from organisms most directly?

Cellular respiration. Organisms release $CO_2$ when breaking down glucose for energy.
Which process releases usable energy from glucose for cell activities?

Cellular respiration. Breaks down glucose molecules to release ATP for cell work.
What happens to most energy at each trophic level in a food chain?

It is lost as heat through life processes. Only ~10% transfers up; rest powers metabolism and movement.
What is the main cellular process that releases usable energy from glucose?

Cellular respiration. Breaks down glucose to release ATP for cellular work.
What is a decomposer, and what is its role in matter cycling?

An organism that breaks down dead matter and returns nutrients. Recycles matter by breaking down dead organisms into nutrients.
Which organism is the primary consumer in the chain: algae → zooplankton → small fish?

Zooplankton. Eats algae (producer), making it the first consumer.
Which statement is correct: energy cycles in ecosystems, or energy flows one-way through ecosystems?

Energy flows one-way through ecosystems. Energy enters as sunlight and exits as heat.
What is a decomposer, and what is its role in matter cycling?

Organism that breaks down dead matter and returns nutrients. Bacteria and fungi recycle nutrients from dead organisms to soil.
What is the main process cells use to release energy from food molecules like glucose?

Cellular respiration. Breaks down glucose to release ATP for cell activities.
Which molecule is the main energy-carrying product made by cellular respiration for cell work?

ATP. Universal energy currency used by all cells.
Which organism is the secondary consumer in this chain: algae → insect larva → fish?

Fish. Second-level consumer that eats the primary consumer.
Which statement best describes how energy moves through a food chain?

Energy flows one-way and decreases at each transfer. Only ~10% transfers between levels; rest lost as heat.
In a food chain Algae → Zooplankton → Small fish, which organism is the producer?

Algae. Makes own food through photosynthesis; base of food chain.
Choose the correct label for the arrows in a food web: energy transfer or matter creation?

Energy transfer. Arrows show energy moving from eaten to eater organisms.
What is the primary source of energy for nearly all food webs on Earth?

The Sun. Solar energy drives photosynthesis, starting most food chains.
Which molecule is the main energy currency used directly by cells?

ATP. Universal energy molecule that powers cellular processes.
What process do cells use to release energy from food to make ATP?

Cellular respiration. Breaks down glucose to produce ATP for cell activities.
Identify the direction of energy transfer in the chain: grass → rabbit → hawk.

From grass to rabbit to hawk. Energy flows from producer to primary to secondary consumer.
Which statement best describes energy flow in ecosystems: cycle or one-way flow?

Energy flows one way; it is not recycled. Energy dissipates as heat and cannot be reused.
What are the main products of cellular respiration?

$CO_2$ , $H_2O$ , and ATP (plus heat). Releases stored energy as ATP while producing waste gases.
Identify the trophic level of grass in the chain: grass → rabbit → fox.

Producer. First trophic level; makes food through photosynthesis.
What is the primary energy-storing molecule made by photosynthesis?

Glucose (sugar). C₆H₁₂O₆ stores chemical energy from photosynthesis.
Which molecule is the main usable energy currency for cells?

ATP. Universal energy molecule that powers cellular processes.
In a food web, which group returns carbon to the air as $CO_2$ during cellular respiration?

All organisms (producers, consumers, and decomposers). Every organism respires, releasing $CO_2$ from organic molecules.
What is a decomposer, and what does it do to dead organisms and wastes?

An organism that breaks them down into simpler substances. Recycles nutrients back to soil for producers to use.
Identify the main evidence that a plant gained mass during growth: CO $_2$ uptake, O $_2$ release, or sunlight absorption?

CO $_2$ uptake. Carbon from CO $_2$ becomes plant biomass during photosynthesis.
What are the products of photosynthesis?

Glucose (sugar) and oxygen. Energy is stored in glucose bonds; oxygen is released as waste.
Which organism is the primary consumer in the chain: algae → zooplankton → fish?

Zooplankton. First-level consumer eats the producer (algae).
What form of energy is transferred when one organism eats another?

Chemical energy stored in biomolecules. Bonds in carbohydrates, proteins, and fats contain energy.
What are the main reactants of cellular respiration?

Glucose and $O_2$ . Breaks down sugar using oxygen to release energy.
Which molecule provides most of the carbon atoms used to build plant biomass?

Carbon dioxide ( $CO_2$ ). Plants fix atmospheric $CO_2$ to build carbohydrates and tissues.
Identify the most direct evidence that decomposers recycle matter in an ecosystem.

They convert dead biomass into simpler nutrients returned to soil or water. Breaking down releases nutrients for producer uptake.
What is the primary source of energy for most ecosystems on Earth?

Sunlight (energy from the Sun). Photosynthesis captures solar energy to start all food chains.
What are the reactants of cellular respiration?

Glucose and oxygen. Cells break down sugar using oxygen to release energy.
What process do producers use to convert light energy into chemical energy in glucose?

Photosynthesis. Converts light energy into chemical energy stored in glucose molecules.
Which option best explains why energy decreases at higher trophic levels in an energy pyramid?

Energy is used for life processes and released as heat. Only ~10% transfers up; rest powers metabolism and becomes heat.
Which gas is released as a product of cellular respiration in most organisms?

Carbon dioxide ( $CO_2$ ). Waste product when glucose is broken down for energy.
Which type of organism is a consumer in a food chain?

A heterotroph that eats other organisms. Cannot make own food; must consume other organisms for energy.
Identify the trophic level of grass in the chain: grass → rabbit → fox.

Producer. First trophic level that makes food through photosynthesis.
Which level in a food chain is the first trophic level?

Producers. First level captures energy from sun or chemicals.
What happens to most energy as it moves from one trophic level to the next?

Most is lost as heat; only a small fraction is transferred. Only ~10% transfers up; 90% lost to metabolism and heat.
What is the primary energy source for most ecosystems on Earth?

Sunlight (solar energy). Captured by producers through photosynthesis to start food chains.
Which statement best describes how energy moves in ecosystems: cycles or flows?

Energy flows one way through ecosystems. Cannot be recycled; enters as sunlight, exits as heat.
What is the main reason energy decreases at higher trophic levels?

Energy is lost as heat and used for life processes. Organisms use energy for metabolism, movement, and growth.
What cell organelle is the main site of cellular respiration in eukaryotic cells?

Mitochondrion. Contains enzymes for breaking down glucose to produce ATP.
If a food chain is grass → rabbit → fox, what is the rabbit's trophic role?

Primary consumer (herbivore). Eats producers (grass) and is eaten by secondary consumers.
In a food chain, which direction does energy flow: from prey to predator or predator to prey?

From prey to predator. Energy transfers up the food chain when predators eat prey.
What is the definition of a consumer in an ecosystem?

An organism that gets energy by eating other organisms. Cannot produce their own food, so must consume other organisms.
What is the difference between a food chain and a food web?

Chain: one path; web: many connected feeding paths. Chains show linear feeding; webs show interconnected relationships.
Which direction do arrows point in a food chain: from eater to food, or from food to eater?

From food to eater (direction of energy transfer). Shows energy flow from source to recipient.
Which statement best describes how energy moves through a food chain?

Energy flows one-way and is lost as heat. Energy cannot be recycled; it dissipates at each transfer.
What term describes organisms that make their own food from inorganic materials?

Producers (autotrophs). Use photosynthesis to convert inorganic matter into organic food.
In a food chain arrow ( $A \rightarrow B$ ), what does the arrow represent?

Energy and matter moving from $A$ (food) to $B$ (consumer). Arrow shows direction of energy and matter flow.
Which trophic level is always the first level in a food chain?

Producers. They convert solar energy into food for all other levels.
Choose the best claim: When a wolf eats a deer, does the wolf gain the deer's matter, energy, or both?

Both matter and chemical energy. Deer's molecules become wolf's body; energy powers wolf's activities.
What is a food web?

A network of interconnected food chains in an ecosystem. Shows complex feeding relationships between organisms.
What is a decomposer, and what role does it play in matter cycling?

Organism that breaks down dead matter and recycles nutrients. Returns elements to soil/water for producer reuse.
Choose the best evidence that plant matter becomes animal mass after herbivory.

Atoms from plant food are incorporated into animal tissues. Plant molecules become part of animal's body structure.
Which process directly returns carbon to the atmosphere as $CO_2$ : photosynthesis or cellular respiration?

Cellular respiration. Releases $CO_2$ as organisms break down glucose for energy.
What is the term for organisms that make their own food from sunlight or chemicals?

Autotrophs (producers). Self-feeders that convert inorganic matter to organic compounds.
Identify the direction of arrows in a food chain: from predator to prey or prey to predator?

From food to eater (prey to predator). Arrows show energy flow direction from source to consumer.
What happens to most energy between trophic levels when one organism eats another?

It is lost as heat and used for life processes. Only ~10% transfers up; rest powers metabolism and movement.
Which direction do arrows point in a food chain or food web?

From food source to consumer (direction of energy transfer). Shows who eats whom in the ecosystem.
Which evidence best supports that energy decreases at higher trophic levels: biomass or DNA similarity?

Biomass (or energy) pyramid data. Biomass decreases at each level due to energy loss as heat.
Identify the trophic level of rabbit in the chain: grass → rabbit → fox.

Primary consumer. Herbivore that directly eats producers.
Which choice is the best evidence that matter is conserved in a closed ecosystem?

Total mass stays constant even as matter changes form. Law of conservation of mass applies to ecosystems.
What happens to most energy at each trophic level transfer in a food chain?

It is lost as heat through metabolism. Only ~10% transfers up; rest powers metabolism and becomes heat.
What is the correct word for an organism that gets energy by consuming other organisms?

Heterotroph (consumer). Must eat other organisms because they cannot produce their own food.
What is the difference between energy flow and matter cycling in ecosystems?

Energy flows one-way; matter cycles and is reused. Energy dissipates as heat; atoms recycle endlessly.
Which molecules are products of photosynthesis?

Glucose and oxygen. Light energy transforms reactants into these organic products.
What are the products of photosynthesis?

Glucose and oxygen. Sugar stores energy; oxygen released as waste product.
What is the correct term for an organism that must eat other organisms for energy and matter?

Consumer (heterotroph). Cannot produce own food, so depends on consuming others.
What pigment in chloroplasts absorbs light energy for photosynthesis?

Chlorophyll. Green pigment that captures light energy to power photosynthesis.
Identify the form of matter that decomposers return to soil and water for reuse.

Inorganic nutrients (minerals such as nitrogen and phosphorus compounds). Decomposition releases elements as simple compounds.
Which option best traces carbon atoms from air into animals: $CO_2 \rightarrow$ plant sugar $\rightarrow$ animal tissues?

$CO_2 \rightarrow$ plants (photosynthesis) $\rightarrow$ animals (feeding). Carbon enters plants as $CO_2$ , becomes sugar, then animal tissue.
Which observation is evidence that plants gain mass mainly from carbon dioxide?

Plant mass increases while soil mass changes very little. Van Helmont's experiment showed soil isn't the main source.
Which type of organism is a producer, and what is its energy source?

Autotroph; sunlight or chemical energy. Makes own food from inorganic sources without eating others.
Identify the correct order for a simple chain: grass, rabbit, fox (from first to last).

Grass → rabbit → fox. Producer eaten by primary consumer eaten by secondary consumer.
What is the primary source of energy for most ecosystems on Earth?

Sunlight (solar energy). Captured by producers through photosynthesis to power food chains.
Which option is the best evidence that plants gain mass mostly from air, not soil?

Carbon in plant biomass comes mainly from $\text{CO}_2$ . Photosynthesis incorporates atmospheric carbon into biomass.
Identify the trophic level of a hawk that eats snakes that eat mice that eat seeds.

Tertiary consumer. Third consumer level: eats secondary consumers (snakes).
What cell organelle is the main site of cellular respiration in most eukaryotic cells?

Mitochondrion. Breaks down glucose to produce ATP for cellular energy.
Identify the correct direction of energy flow in a food chain: consumer to producer or producer to consumer?

Producer to consumer. Energy moves up trophic levels from plants to herbivores to carnivores.
What is the primary source of energy for most food webs on Earth?

Sunlight (solar energy). Producers convert light energy into chemical energy for all organisms.
Identify the trophic roles in this chain: grass → rabbit → fox.

Producer → primary consumer → secondary consumer. Grass makes food, rabbit eats grass, fox eats rabbit.
Which molecules are reactants in cellular respiration?

Glucose and oxygen. These molecules contain stored chemical energy to release.
Which molecules are reactants in photosynthesis that provide atoms for glucose?

Carbon dioxide and water. These inorganic molecules supply C, H, and O atoms.
Which molecule provides carbon atoms that become part of plant sugars in photosynthesis?

Carbon dioxide ( $CO_2$ ). Carbon from air becomes carbon in glucose during photosynthesis.
Which gas is released as a product of photosynthesis and can be measured as evidence of the process?

O $_2$ . Waste product shows photosynthesis is actively occurring.
Which statement best describes how matter moves through a food chain?

Matter is transferred and recycled. Atoms cycle through organisms but are never destroyed.
Which diagram label best shows where matter is recycled in a food web: producers, consumers, or decomposers?

Decomposers. Break down dead organisms, returning nutrients to soil for producers.
What law supports the claim that matter is conserved in organisms and ecosystems?

Law of Conservation of Mass. Matter cannot be created or destroyed, only rearranged.
Which term names the feeding level in a food chain (producer, primary consumer, secondary consumer)?

Trophic level. Each level represents organisms with the same feeding position.
What term describes organisms that break down dead matter and recycle nutrients?

Decomposer. Bacteria and fungi that return nutrients to soil.
What are the reactants of cellular respiration?

Glucose and oxygen. These react in mitochondria to produce ATP, water, and $CO_2$ .
What process releases usable energy from glucose for cell work by producing ATP?

Cellular respiration. Breaks glucose bonds to transfer energy into ATP molecules.
What is the primary source of energy for most food webs on Earth?

Sunlight from the Sun. Producers capture this energy to start all food chains.
What is the role of a decomposer in cycling matter?

Breaks down dead matter and returns nutrients to soil/water. Recycles carbon, nitrogen, and other elements.

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