Topic 9 Ecosystems and Material Cycles

Question 1

What is an ecosystem?

Answer 1

An ecosystem is a community of living organisms (biotic factors) interacting with their physical environment (abiotic factors).

Question 2

What is meant by the term “interdependence” in an ecosystem?

Answer 2

Interdependence refers to the reliance of organisms on each other for food, shelter, pollination, seed dispersal, and other needs for survival.

Question 3

What is a population in terms of an ecosystem?

Answer 3

A population is a group of individuals of the same species living in a specific area.

Question 4

What is the difference between a habitat and a niche?

Answer 4

A habitat is the physical environment where an organism lives, while a niche is the role and position an organism has in its environment, including its interactions with other species.

Question 5

What is meant by “biotic factors” in an ecosystem? Give an example

Answer 5

Biotic factors are living components of an ecosystem, such as plants, animals, and bacteria. An example is predation.

Question 6

What is a food chain?

Answer 6

A food chain is a linear sequence showing how energy and nutrients flow from one organism to another in an ecosystem.

Question 7

What is the role of producers in a food chain?

Answer 7

Producers, like plants and algae, make their own food through photosynthesis and provide energy for the rest of the food chain.

Question 8

What are primary consumers, and what do they eat?

Answer 8

Primary consumers are herbivores that eat producers (plants).

Question 9

What is the difference between a food chain and a food web?

Answer 9

A food chain shows a single path of energy flow, while a food web shows the interconnected feeding relationships in an ecosystem.

Question 10

Why is energy lost at each trophic level in a food chain?

Answer 10

Energy is lost at each trophic level due to processes like respiration, movement, and heat production, as well as waste products (undigested material).

Question 11

What is a predator-prey relationship?

Answer 11

It is an interaction where a predator hunts and kills prey for food, helping regulate population sizes in an ecosystem.

Question 12

What is competition in an ecosystem?

Answer 12

Competition occurs when organisms vie for the same resources, such as food, water, shelter, or mates, within a habitat.

Question 13

What is interspecific competition?

Answer 13

Competition between different species for the same resources.

Question 14

What is intraspecific competition?

Answer 14

Competition between individuals of the same species for resources.

Question 15

How can an increase in prey population affect predator numbers?

Answer 15

An increase in prey population can provide more food for predators, leading to an increase in predator numbers.

Question 16

What are the main processes involved in the carbon cycle?

Answer 16

Photosynthesis, respiration, combustion, and decomposition.

Question 17

How does photosynthesis contribute to the carbon cycle?

Answer 17

Plants take in carbon dioxide from the atmosphere and use it to make glucose during photosynthesis, locking carbon in organic molecules.

Question 18

How does respiration affect the carbon cycle?

Answer 18

Respiration by plants, animals, and decomposers releases carbon dioxide back into the atmosphere.

Question 19

What role do decomposers play in the carbon cycle?

Answer 19

Decomposers break down dead organisms, returning carbon to the soil and releasing carbon dioxide into the atmosphere through respiration.

Question 20

How does combustion of fossil fuels affect the carbon cycle?

Answer 20

Burning fossil fuels releases large amounts of carbon dioxide into the atmosphere, contributing to the greenhouse effect and global warming.

Question 21

Why is nitrogen important for living organisms?

Answer 21

Nitrogen is needed to make proteins and DNA, which are essential for growth and reproduction.

Question 22

What is nitrogen fixation, and which organisms are involved?

Answer 22

Nitrogen fixation is the process by which nitrogen gas from the atmosphere is converted into ammonia or nitrates. Nitrogen-fixing bacteria in soil or root nodules of legumes perform this task.

Question 23

What is the role of nitrifying bacteria in the nitrogen cycle?

Answer 23

Nitrifying bacteria convert ammonia into nitrites and then nitrates, which plants can absorb.

Question 24

What is the role of denitrifying bacteria in the nitrogen cycle?

Answer 24

Denitrifying bacteria convert nitrates back into nitrogen gas, releasing it into the atmosphere.

Question 25

How do animals obtain nitrogen?

Answer 25

Animals obtain nitrogen by eating plants or other animals, as nitrogen is present in the proteins of their food.

Question 26

How does deforestation affect ecosystems and material cycles?

Answer 26

Deforestation disrupts ecosystems by removing habitats and decreases the rate of photosynthesis, leading to higher carbon dioxide levels and altered carbon and water cycles.

Question 27

What is eutrophication, and how can it affect aquatic ecosystems?

Answer 27

Eutrophication is the process where excess nutrients (from fertilizers) run into water bodies, causing algae blooms that reduce oxygen levels, leading to the death of aquatic organisms.

Question 28

How does climate change affect ecosystems?

Answer 28

Climate change can alter habitats, affect species distribution, cause extinctions, and disrupt food chains due to changes in temperature, rainfall patterns, and sea levels.

Question 29

What is bioaccumulation?

Answer 29

Bioaccumulation is the build-up of toxic substances, such as pesticides, in the tissues of organisms, which can be passed along the food chain and affect predators at higher trophic levels.

Question 30

What is biodiversity, and why is it important for ecosystems?

Answer 30

Biodiversity refers to the variety of living organisms in an ecosystem. It is important because it helps maintain ecosystem stability and resilience against environmental changes.

Question 31

What are the main processes of the water cycle?

Answer 31

Evaporation, condensation, precipitation, and transpiration.

Question 32

What is transpiration?

Answer 32

Transpiration is the process where plants lose water vapor from their leaves, contributing to the water cycle.

Question 33

How does evaporation contribute to the water cycle?

Answer 33

Water from oceans, lakes, and rivers is heated by the sun and evaporates, turning into water vapor and entering the atmosphere.

Question 34

What is precipitation, and how does it return water to the Earth?

Answer 34

Precipitation occurs when water vapor in clouds condenses into water droplets and falls back to the Earth as rain, snow, or hail.

Question 35

How do human activities like urbanization affect the water cycle?

Answer 35

Urbanization can increase surface runoff and reduce infiltration of water into the ground, disrupting natural water flow and potentially leading to flooding.