Year 9 Respiration and Ecosystems Worksheet - Beginner

Year 9 Respiration and Ecosystems worksheet for Year 9 (Key Stage 3 / Year 7-9 (Ages 11-14)). Beginner level science practice, aligned to the UK National Curriculum. Print-ready with answer key included.

Science•Key Stage 3 / Year 7-9 (Ages 11-14)•Respiration and Ecosystemsbeginner

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Respiration & Ecosystems: Year 9 Science

Ages 13–14 | Beginner level

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Instructions: Work through each activity, using the guidance to build your understanding. Read the data and scenarios carefully, and show your reasoning in the answer spaces. Use scientific terms where you can.

Aerobic Respiration

Use the word bank to complete the equation, then answer the questions. Remember that aerobic respiration releases energy from glucose using oxygen. Write a word or short phrase in each box.

Word bank: carbon dioxide, energy, glucose, oxygen, water

1. Complete the word equation: glucose + ___ → ___ + ___ + ___.

2. Which gas is taken in for aerobic respiration?

3. In which part of a cell does most aerobic respiration take place?

4. Name one process in the body that needs energy released by respiration.

Anaerobic Respiration: Humans and Microorganisms

Compare what happens when cells respire without enough oxygen. Use the descriptions in each question and give concise answers. For the equation, write the missing product or products.

1. During vigorous exercise, human muscle cells respire anaerobically. Complete: glucose → lactic acid + ___.

2. What substance can build up in muscles during anaerobic respiration in humans?

3. Yeast respires anaerobically in fermentation. Complete: glucose → ethanol + ___.

4. Name the gas released by yeast during fermentation.

5. Give one use of fermentation by yeast in food production.

Respiration and Photosynthesis: Compare

Use your knowledge of the two processes to complete the comparison. Remember that photosynthesis stores energy in glucose, whereas respiration releases energy from glucose. Give a concise answer in each box.

1. Which process uses carbon dioxide and water to make glucose and oxygen?

2. Which process releases energy from glucose?

3. Name the green substance that absorbs light energy for photosynthesis.

4. State one way the word equations for photosynthesis and aerobic respiration are linked.

Ecosystems and Interdependence

Read the food-chain information and use it to explain how organisms depend on one another. A food chain shows one feeding relationship; an ecosystem contains many interacting organisms and their environment.

Food chain: grass → rabbit → fox

1. Which organism is the producer?

2. What is the rabbit’s food source in this chain?

3. Predict what may happen to the fox population if the rabbit population decreases greatly. Give a reason.

4. Name one non-living environmental factor that could affect the growth of the grass.

Toxic Materials in Food Chains

Study the measurements in the table. The values show the concentration of a persistent toxic chemical in organisms from one food chain. Compare the values and explain the pattern using the idea of biomagnification.

Organism	Chemical concentration (arbitrary units)
Water	0.02
Plankton	0.2
Small fish	2
Large fish	20
Predatory bird	200

1. Which organism has the greatest chemical concentration?

2. How many times greater is the concentration in the large fish than in the small fish?

3. Describe the overall pattern in chemical concentration along this food chain.

4. Explain why a persistent toxic material may reach its highest concentration in a top predator.

Answer Key

Activity 1: 1. oxygen; carbon dioxide; water; energy (the equation is glucose + oxygen → carbon dioxide + water + energy) ; 2. Oxygen ; 3. Mitochondria ; 4. Any valid example, such as muscle contraction, maintaining body temperature, growth or active transport

Activity 2: 1. Energy ; 2. Lactic acid ; 3. Carbon dioxide ; 4. Carbon dioxide ; 5. Any valid example, such as bread-making or brewing

Activity 3: 1. Photosynthesis ; 2. Respiration ; 3. Chlorophyll ; 4. The products of photosynthesis (glucose and oxygen) are reactants for aerobic respiration, and the products of aerobic respiration (carbon dioxide and water) are reactants for photosynthesis

Activity 4: 1. Grass ; 2. Grass ; 3. The fox population may decrease because less food is available ; 4. Any valid non-living factor, such as light intensity, water availability, temperature or mineral availability

Activity 5: 1. Predatory bird ; 2. 10 times ; 3. Concentration increases at each successive stage, from water to the top predator ; 4. The toxic material is persistent and is not readily broken down or excreted, so it accumulates in organisms and becomes more concentrated in predators that eat many contaminated prey