How Environmental Conditions Affect Plant Growth — Answers
Answer sheet with model answers and success criteria for the Year 7 living things & life cycles worksheet.
Success TutoringWorksheetsAnswer sheetYear 7 · Science · Living Things & Life CyclesHow Environmental Conditions Affect Plant Growth — Answers
Part A: Conditions for life
Read the passage, then answer the questions.
Living things need the right physical conditions to grow and survive. Important conditions include light, water, temperature, air and nutrients in the soil.
Each living thing has a range of conditions it can survive in. If conditions are too extreme — too hot, too cold, too dry, too wet or too salty — it grows poorly or dies.
Animals are affected too. Many frogs need moist places so their skin does not dry out, and some animals hibernate or migrate to survive cold winters.
- Ato keep warm at night
- Bto make their own food by photosynthesis
- Cto help their roots find water
- Dto scare away insects
Answer: to make their own food by photosynthesis
Plants use light energy, water and carbon dioxide to make sugar (food) in a process called photosynthesis.
- AIt grows greener and stronger.
- BIt turns pale and weak, because it cannot make enough food.
- CIt grows flowers straight away.
- DNothing changes.
Answer: It turns pale and weak, because it cannot make enough food.
Without light the plant cannot make food by photosynthesis, so it becomes pale, thin and weak.
- ASalt makes the soil too cold.
- BSalt makes it hard for most plant roots to take up water.
- CSalt blocks out sunlight.
- DSalt is food that plants eat too much of.
Answer: Salt makes it hard for most plant roots to take up water.
Salty soil draws water away from roots, so most plants cannot take in enough water. Only specially adapted plants can survive.
- temperature
- water
- light
- soil nutrients
- very cold weather can freeze plant cells and slow animals down
- help plants grow strong leaves and stems
- too little causes wilting; too much can rot roots
- plants need it to make food
Answer: temperature → very cold weather can freeze plant cells and slow animals down; water → too little causes wilting; too much can rot roots; light → plants need it to make food; soil nutrients → help plants grow strong leaves and stems
Part B: A plant growth investigation
Use the results to answer the questions.
Investigation: How does the amount of water affect the growth of bean seedlings?
Five groups of three bean seedlings were grown in the same type of pot, with the same soil, on the same sunny windowsill. Each group was given a different amount of water every day. After 14 days the height of each seedling was measured.
Average height after 14 days
0 mL per day: 0 cm (seedlings died)
20 mL per day: 6 cm
40 mL per day: 11 cm
60 mL per day: heights 11 cm, 13 cm and 12 cm — average ?
80 mL per day: 7 cm (soil stayed soggy)
Answer: 12 cm
- 11 + 13 + 12 = 36
- 36 ÷ 3 = 12 cm
Answer: The amount of water given each day.
Answer: The height of the seedlings after 14 days.
Answer: Any two of: type of seed/plant, type of pot, type and amount of soil, position (light), temperature, number of days.
Answer: 60
- Ato use up spare seeds
- Bso the results are more reliable — one unusual plant will not change the conclusion much
- Cso the pots look full
- Dbecause beans only grow in threes
Answer: so the results are more reliable — one unusual plant will not change the conclusion much
Repeating measurements and averaging them makes results more reliable.
Answer: False
Growth increased up to 60 mL, but at 80 mL the seedlings were shorter. Too much water can harm a plant.
Part C: Apply it
Answer: True
Desert plants such as cacti are adapted to survive very dry conditions.
Answer: The soil stayed soggy, so the roots could not get enough air (oxygen) and may have started to rot.
Model answer: I would change the temperature by placing identical trays of seeds in three places: a fridge, a room at normal temperature and a warm spot. I would measure how many days it takes for each seed to sprout (or count how many have sprouted each day). I would keep the type and number of seeds, the soil, the amount of water and the container the same. To make the results reliable I would use at least ten seeds in each tray and calculate the average number of days, and repeat the test if possible.
Success criteria:
- Independent variable: temperature (with sensible values)
- Dependent variable: time to sprout or number sprouted
- At least two controlled variables
- Repeats or uses many seeds for reliability
Marking tips
- Give credit for correct method even when the final answer slips — the working shows where the thinking went right.
- For open-ended tasks, use the success criteria as a checklist rather than looking for one "right" answer.
- Celebrate what went well first, then pick one thing to work on next.
Great work. Here's what to try next: