Ecosystems

Question 1

What are the six factors of the physical (abiotic) factors?

Answer 1

Light, Temperature, Water, air, mineral salts and salinty and pH

Question 2

Why is light essential for plants and animals such as sheep and what are the reactions of earthworms to light?

Answer 2

Plants need light to make food through photosynthesis.
Sheep need light to see so that they can move around, find food and avoid danger.
Earthworms burrow deeply into the soil to avoid night and come out only at night to feed and reproduce.

Question 3

How does animals such as (migratory birds and polar bears) adapt to survive under extreme conditions? (Colder areas)

Answer 3

Migratory birds migrate to countries with warmer climates (SG) to avoid the cold winters.

Polar bears have a thick coat of fur to keep themselves warm in the polar region.

Question 4

How does plants such as cactus and animals like desert fox, adapt to environments with low water supply?

Answer 4

The cactus has small spiny leaves that reduce water loss. A thick fleshy stem helps store water and carries out photosynthesis.

The desert fox hunts during night time to minimise water loss.

Question 5

How do some organisms like mangroves and mudskippers adapt to survive in low-oxygen habitats.

Answer 5

Mangroves have aerial roots with tiny pores that allow gaseous exchange.

Mudskippers have enlarged gill chambers that can retain a bubble of air. They use this bubble of air as oxygen supply when they are on land.

Question 6

How do plants and turtles get rid of excess salts in the water?

Answer 6

Plants growing near the sea lake take in a lot of salt along with water. The cordgrass gets rid of excess salt through its leaves.

Turtles remove excess salt through salt glands in their eyes.

Question 7

What is the three different interrelationships between organisms to keep the balance in the habitat?

Answer 7

Predator-prey relationship
Parasitism
Mutualism

Question 8

What is parasitism?

Answer 8

Parasitism is a relationship between two organisms in which one (the parasite) benefits at the expense of the other (the host) A parasite normally does some harm to its host.

Question 9

What is mutualism?

Answer 9

Mutualism is a relationship between two organisms in which both organisms benefit from each other.

Question 10

Which of these options is parasitism?

(A) Fleas are blood-sucking parasites usually found on mammals.

(B) Butterflies feed on nectar from flowers. In exchange, the butterflies help the flowers in pollination.

Answer 10

(A) is parasitism
(B) is mutualism

Question 11

What is the difference between food chain and food web?

Answer 11

A food chain shows the feeding relationship between organisms. It also shows the path of energy flow from the green plant to the consumer.

While
A food web is made of inter-linked food chains.

Question 12

What is the four trophies levels?

Answer 12

Producers: green plants.
Primary consumers: Herbivores (eat plant) and omnivores (eat plant and animals)
Secondary consumers: carnivores (animals that eat animals) and omnivores (eat plant and animals)
Tertiary consumers (carnivores, omnivores)

Question 13

What is the difference between respiration and photosynthesis?

Conditions needed: …….
Conversion………
Equation……….
Function:………….

Answer 13

Conditions needed:
Respiration: Food molecules (glucose) and oxygen
Photosynthesis: Light energy, carbon dioxide and water.

Conversion:
Respiration
Chemical energy stored in food is released. Animals—- energy converted to other forms——heat—-respiration occurs in every plant and animal cell.

Photosynthesis
Light energy converted into chemical energy and stored as complex nutrients like carbohydrates. Photosynthesis occurs only in plants that contain chlorophyll. Chlorophyll, found mainly in the leaves, is the pigment that absorbs light.

Equation:
Respiration
Glucose+ Oxygen——> Carbon dioxide +Water

Photosynthesis
Carbon dioxide+ Water-(Chlorophyll+ Light energy)
Glucose +Oxygen

Function
Respiration
The carbon dioxide released during respiration and breathing is used by plants for photosynthesis.

Photosynthesis:
The oxygen released during photosynthesis is used by other plants and animals for respiration.

Question 14

What is a decomposer?

Answer 14

Decomposers break down the complex nutrients in faeces and dead bodies of plants and animals.

Question 15

What is some examples of decomposers?

Answer 15

Fungi and bacteria

Question 16

What is released during the process of decomposing?

Answer 16

Carbon dioxide which escapes into the atmosphere

Soluble mineral salts that dissolve in the soil water

Question 17

What is a scavenger?

Answer 17

Scavengers are organisms that feed on dead or decaying matter and help decomposers to break down dead organisms into simple substances faster.

Question 18

How much percentage of energy is being lost from one organism to another?

Answer 18

10%

Question 19

Convert J to kJ: 1800J=

Answer 19

1.8kJ

Question 20

Explain why a typical food chain does not have more than five trophic levels.

Answer 20

A typical food chain does not have more than five trophic levels as there is insufficient energy to be available to the next trophic level and there is only 10%, a small amount of energy that is transferred

Question 21

A smallest amount of energy is transferred from
(A) producers to primary consumers
(B) primary consumers to secondary consumers

Answer 21

(B) primary consumers to secondary consumers

Question 22

The largest amount of energy lost to the environment from the
(A) producers to the environment
(B) primary consumers to the environment
(C) secondary consumers to the environment

Answer 22

(A) producers to the environment

Question 23

Account for the difference between the amount of energy absorbed and the amount actually converted into energy (fixed) by producers.

Answer 23

Most of the energy absorbed by the producers is not used in photosynthesis. (Depends on data given in figure) This excess energy which is not fixed is lost as heat.

Question 24

What is a habitat?

Answer 24

A habitat is where an organism lives. It provides everything that the organism needs.

Question 25

What does population and community mean in ecosystem?

Answer 25

A group of organisms of the same type is called a population. Different population living together in the same habitat forms a community of organisms.

Question 26

What is an ecosystem?

Answer 26

An ecosystem is made up of the community of organisms interacting with one another and with their environment.

Question 27

The environment of an organism comprises the non living or ______ environment, as well as the living or ____ environment.

Answer 27

The environment of an organism comprises the non-living or abiotic environment, as well as the living or biotic environment.

Question 28

Why is the availability of light ultimately important to any ecosystem?

Answer 28

Primary producers/plants need light to photosynthesise, to trap energy derived from light within biomolecules and this energy can be passed down to primary consumers that feed on the producers, and subsequently to secondary and tertiary consumers.

Question 29

What does adaptation mean?

Answer 29

Adjustment to increases chances of survival in an environment/habitat.

Question 30

Explain one way in which polar bears have adapted to their Arctic environment.

Answer 30

Polar bears hibernate and goes into a deep sleep. This drops the polar bears body temperature and slows down the heartbeat of the polar bear. Allowing the bear to conserve energy and avoid the need to eat.

Question 31

In some deserts, many animals are nocturnal, or active at night.
Suggest why this may be so.

Answer 31

Avoid the extreme high temperatures during the day.

Question 32

Mangroves grow in wetlands or swamps. What physical factor is lacking in this habitat?

Answer 32

Oxygen. (Air)

Question 33

Suggest why aquatic habitats tend to see an increase in acidity during the night.

Answer 33

Plants stop photosynthesis/stop using carbon dioxide ar night, leading to an accumulation of carbon dioxide which dissolves to produce an acid.

Question 34

Which of the following correctly describes a process of nutrient or energy flow in an ecosystem?

A. Carbohydrates are transferred directly from primary consumers to secondary consumers in the absence of decomposers.

B. Energy flows continuously and reversibly from decomposers to producers through nutrient cycling.

C. Nitrogenous compounds, rather than proteins, are indirectly passed from primary consumers to producers through the process of decomposition.

D. Water is produced by producers during photosynthesis and then directly transferred to primary consumers.

Answer 34

Explanation of Each Option:
A. Carbohydrates are transferred directly from primary consumers to secondary consumers in the absence of decomposers.

Incorrect. Carbohydrates are not directly transferred from primary consumers to secondary consumers; instead, energy flows from primary consumers to secondary consumers through consumption. Decomposers are important in breaking down dead organisms and recycling nutrients.
B. Energy flows continuously and reversibly from decomposers to producers through nutrient cycling.

Incorrect. Energy flow in an ecosystem is unidirectional, not reversible. It moves from producers to primary consumers and then to secondary consumers. Decomposers recycle nutrients but do not directly transfer energy to producers.
C. Nitrogenous compounds, rather than proteins, are indirectly passed from primary consumers to producers through the process of decomposition.

Correct. When primary consumers die, decomposers break down their bodies, releasing nitrogenous compounds (like nitrates) into the soil. Plants then absorb these compounds to synthesize proteins, indirectly linking primary consumers to producers.
D. Water is produced by producers during photosynthesis and then directly transferred to primary consumers.

Incorrect. Producers (plants) do release water as a byproduct of photosynthesis, but this water is not directly transferred to primary consumers; it evaporates into the atmosphere and is part of the water cycle.
Correct Answer:
C. Nitrogenous compounds, rather than proteins, are indirectly passed from primary consumers to producers through the process of decomposition.

This option accurately reflects the nutrient cycling process where decomposers break down organic matter, releasing nitrogen compounds that plants can use.

Take Note: Qn and ans is generated from ChatGPT from an adapted qn in FA

Question 35

Which statement correctly describes factors that are passed on in an ecosystem?
A Carbohydrates are passed from decomposers to producers.
B Energy is passed from secondary consumers to primary consumers.
C Proteins are passed from primary consumers to producers.
D Water is passed from respiring decomposers to producers.

Answer 35

The correct answer is D: Water is passed from respiring decomposers to producers.

Here’s why:

A is incorrect: Carbohydrates are not passed from decomposers to producers. Producers create their own carbohydrates through photosynthesis, and decomposers break down dead organisms but don’t directly provide carbohydrates to producers.
B is incorrect: Energy flows in one direction in an ecosystem—from primary producers to primary consumers and then to secondary consumers, not the other way around.
C is incorrect: Proteins are not passed directly from primary consumers to producers. Instead, when organisms die, decomposers break down proteins into simpler forms, such as amino acids and nitrogen, which can then be absorbed by producers.
D is correct: Water, as part of the water cycle, is released during respiration by decomposers and is available for producers (plants) to take up from the environment for processes like photosynthesis.

Explanation from ChatGPT

Question 36

How do you answer Explain which is the most efficient food chain in the food web.

Answer 36

Comparison of food chains/trophic levels

1. Least number of trophic levels.
2. Shortest food chain
3. Four trophic levels while other food chains in the food web have five trophic levels (depends on qn)
4. About 90% of energy is lost to the environment as heat and waste.
5. About 10% of energy gets transferred from one trophic level to another as energy is lost as heat and wasted so more energy from producers is passed on to the ___ in this food chain as compared to the other food chains.

Question 37

Explain how an increase in the amount of carbon dioxide and methane released into the atmosphere may be contributing towards the predicted increase in mean temperature shown in the table. (Based on data, so for this flashcard just explain)

Answer 37

Carbon dioxide and/or methane are greenhouse gases which trap heat or infrared/thermal radiation, reflected, re-radiated from Earth’s surface.

Question 38

Explain why temperatures below 0 degrees celcius would be unsuitable for most organisms.

Answer 38

Water freezes below 0 degree celcius, difficultly in accessing/taking in liquid water for survival, and as solvent for many metabolic reactions are required, it would result in cell dehydration/cell burst when water in cells expand when frozen.

rate of metabolic reactions will be low, particles in cell cytoplasm have low kinetic energy/enzymes inactivate.

Question 39

When calculating the energy in an organism and representing it, can it be kJ?

Answer 39

No, it should be kJ (with a line above J)

Question 40

What do you call an organism that feeds on plant? Predators can?

Answer 40

No, predators are usually required to hunt for food, but organism that feeds on plant (primary consumers) do not need to hunt for food since plants cannot move.

Question 41

What is bioremediation?

Answer 41

Bioremediation is the process of using micro-organisms, such as bacteria or fungi, to destroy contaminants in polluted soil or water. An example of bioremediation would be to use the Pseudomonas and Bacillus bacteria to digest organic compounds and clean up oil spills.
Most bacteria found in soil are decomposes. These decomposes may also be used in processes such as bioremediation.

Question 42

What is conversation and what are some examples of conservation?

Answer 42

Protecting and preserving the environment is called conservation.
Conservation reduces global warming and disruption of natural cycles.
Conservation protects different kinds of plants and animals including marine life.
Conservation ensures the preservation of tropical rainforests.