Chapter 12 Science Workbook

Question 1

Why is it important to conserve our environment

Answer 1

We depend on Earth for food, our resources/ raw materials (e,g, metals, limestones) and air and water to survive

Question 2

How does a wet and humid climate help in plant growth

Answer 2

• water is (always) available for plants to use for photosynthesis
• needed for photosynthesis to occur and produce food for the plant

Question 3

How does the availability of sunlight for eight to nine hours a day help in plants growth

Answer 3

• sunlight is available for long hours which allows photosynthesis to take place for longer periods of time
• produce more food for plants to grow more/faster

Question 4

How does the fertile soil help in plant growth

Answer 4

The fertile top layer of soil provides Minerals/mineral salts which are essential for growth

Question 5

Explain how a decrease in the overall amount of rainfall will affect plants and animals

Answer 5

Less water available for plants for photosynthesis, less food produced by plants. Less water available to the animals for drinking, animals die from thirst/dehydration

Question 6

How does acid rain affect ecosystems in forests and ponds

Answer 6

Plants do not have enough nutrients and are not able to grow properly as damaged roots are unable to absorb water and mineral salts causing plants to grow slower/die as the nutrients are washed away from the soil by the acid rain.
Marine organisms cannot survive in water that is too acidic/out or the pH range they usually live in.

Question 7

How does colourless fur help the polar bear to survive

Answer 7

The colourless fur helps the polar bear to camouflage/matches that of ice making it difficult to be spotted by predators/preys

Question 8

How do the two-layers of fur help the polar bears to survive & How does the thick layer of fat help the polar bear to survive

Answer 8

Trap air, which is an insulator/poor conductor of heat, reduce heat loss by conduction this keep the polar bear warm in very cold conditions

Question 9

How does climate change and changes in the environment affect the survival of polar bears

Answer 9

Warmer water results in less sea ice. Less sea ice for the polar bears to hunt for seals, hence no food source. Less sea ice for polar bears to live and hide from predators. They also need to swim further to find food -> younger polar bears may not survive

Question 10

Physical factors of an environment that will affect the numbers of prey and predators

Answer 10

Temperature that can be tolerated
Availability of light
Oxygen
Places to hide

(TB)
F ood
A ir
T emperature

L ight 
A cidity 
M inerals 
A lkalinity 
(or pH)

Question 11

Example of lower availability of water affecting number of preys and predators in an ecosystem

Answer 11

Lower availability of water may result in more animals gathering around remaining lakes/ponds, making it easier for predators to hunt. In the short run, this could reduce the number of prey available for predators

Question 12

Example of availability of light affecting numbers of prey and predators

Answer 12

Lower availability of light will reduce the growth of producers that herbivores feed on, this in turn will reduce the number of prey available for predators

Question 13

How does deforestation affect the environment (4)

Answer 13

1) Deforestation causes climate change
2) Animals lose their habitats
3) and food source -> die
4) increase in amount of carbon dioxide as fewer trees are around to absorb carbon dioxide

Question 14

How do cars and transportation affect the environment

Answer 14

Release greenhouse gases that speed up climate change

Release gases that pollute the air

Question 15

What does burning of fossil fuels do

Answer 15

• release greenhouse gases/ carbon dioxide gas that causes climate change
• extraction and processing fossil fuels causes pollution

Question 16

Explain how microplastics can affect the food web

Answer 16

• (ingestion of microplastics by manga rays, baleen whales, barnacles and clams) may affect their growth/development/reproduction
• cause organisms to die and become lower in numbers/extinct
• increase in population of plankton as there are fewer organisms feeding on it
• decrease in population of crabs and sharks due to decrease in their prey population

Question 17

Suggest how microplastics affect humans (2)

Answer 17

1) Microplastics affect our food supply as there are fewer seafood available
2) Ingestion of microplastics could also affect our health

Question 18

Three ways we can reduce our negative impact of ecosystems

Answer 18

Use public transport
Use alternative sources of energy
Reduce consumption

Question 19

What is the role of ~ in the food chain

Answer 19

• prey
• producer
• predator

Question 20

Suggest the effect(s) on the ecosystem if there is a sudden drop in the number of tuna in the ocean

Answer 20

The population of horse mackerel will increase

• > cause population of shrimp to decrease as horse mackerel is a predator of shrimp
• > increase in population of plankton as shrimp is a predator of plankton

Question 21

What will happen to the animals in the food chain if there is overfishing of horse mackerels

Answer 21

The population of tuna will decrease as tuna are a predator of horse mackerels

• > population of shrimp will increase as horse mackerels are predators of shrimps
• > decrease in the population of plankton as shrimp is the predators of plankton

Question 22

How to prevent overfishing of tuna (as individuals) (3)

Answer 22

1. Consume other types of fish
2. Consider lowering food wastage
3. Consume alternative protein sources e.g. lab-produced protein

Question 23

Describe the effects of using trawlers to fish on the physical environment of the sea (4)

Answer 23

1. Marine organisms that depend on corals for survival will disappear/die
2. Scrapping the sea bottom causes mud and sand to cloud sea water, choking the delicate gills of marine organisms, causing death
3. Ecological balance of the coral ecosystem is affected as overfishing disrupts sea bottom food chains and food webs
4. Noise pollution from the ship’s engine will frighten away most organisms

Question 24

When the no of lions decreased, an increase in the number of humans infected with an intestinal disease observed (usually found in baboons and passed through close contact) suggest why this happened

Answer 24

Not enough food for the increased number of baboons. Baboons go outside of their habitats to look for food
-> increase in contact with human population
Thus there is an increase in the number of humans being infected

Question 25

How is the forest ecosystem affected by deforestation

Answer 25

Fewer producers available -> 
animals lose their habitats/die
Change of physical factors due to burning such as lower availability of light/ph changes in the soil/smoke may cause some organisms to die
Affects predator-prey relationships
Disruptions to food chain/food web

Question 26

what causes a low level of oxygen at the bottom of the water body (algal bloom leading to…)

Answer 26

Water plants at the bottom of the water are unable to photosynthesise due to the lack of sunlight -> no oxygen is produced
Decomposition of dead marine organisms and algae uses up oxygen

Question 27

Why does an increase in temperature that causes less mixing of the top and bottom layers of the water body worsen algal bloom and its effects

Answer 27

Algae bloom allowed to accumulate on top
Bottom water oxygen level drops more/continues to drop as less sunlight reaches the water plants
-> reduced photosynthesis of water plants/ increased decomposition of algae

Question 28

What can be done to prevent algal bloom from occurring

Answer 28

Monitor discharge from factories to ensure that it is treated/filtered off
Monitor levels of nutrients in the water and treat the water to lower nutrient content below algal bloom occurs
Ensure that all sewage pipes from factories do not discharge directly into nearby water bodies