Chapter #18 - Organisms And Their Enviornment

Question 1

Ecology

Answer 1

the study of organisms in their environment.

Question 2

Do organisms live in isolation of each other?

Answer 2

Organisms do not live in isolation of each other. They live in an environment with many other organisms.

Question 3

Habitat

Answer 3

The place where an organism lives

Question 4

Population

Answer 4

A group of organisms of the same species, living in the same area at the same time.

Question 5

Community

Answer 5

All of the populations of all of the different species in an ecosystem.

Question 6

Ecosystem

Answer 6

A unit containing all of the organisms in a community and their environment, interacting together.

Question 7

Niche

Answer 7

the role of an organism in its natural environment. The wayinwhich it interacts with other organisms and with the non-living partsofthe environment.

Question 8

What do organisms do in an ecosystem?

Answer 8

In an ecosystem, each organism has a role.

Question 9

Where does all the energy in an ecosystem originate from?

Answer 9

• The sun
• Sunlight energy is captured by plants and turned into glucose/starch/otherbiological molecules
• Animals get their energy by eating plants

Question 10

Food chain

Answer 10

A diagram showing the flow of energy from one organism to the next, starting with a producer

Question 11

Producer

Answer 11

An organism that makes its own organic nutrients (usually using energy from sunlight, through photosynthesis).

Question 12

Consumer

Answer 12

An organism that gets its nutrients by feeding on other organisms.

Primary – secondary – tertiary – quaternary… etc

Question 13

Food web

Answer 13

a network of interconnected food chains.

Question 14

Which way do the arrows point in a food web?

Answer 14

In the direction of the energy flow

Question 15

How does energy get transferred between trophic levels?

Answer 15

About 10% of the previous trphic level’s energy gets transferred.

Question 16

How does biomass change across trophic levels?

Answer 16

There is less biomass the higher the tropic level. This is because about 10% of the prevous trophic level’s energy is passed on only.

Question 17

Trophic level

Answer 17

Position of an organism in a food chain/web or pyramid.

Question 18

Herbivore

Answer 18

an animal that gets its energy by eating other plants.

Question 19

Carnivore

Answer 19

an animal that gets its energy by eating other animals.

Question 20

Decomposer

Answer 20

an organism that gets its energy from dead or waste organic material.

Question 21

How is energy lost as it is passes through a food web?

Answer 21

• Heat loss from respiration
• Not all parts of the organism are eaten e.g. roots and bones not being eaten
• Not all parts of the organism being eaten is absorbed. When an animal eats another,its digestiveenzymes break downmost of the nutrients,but not all. Some are not digested or absorbed and are just removed as faeces. (Faeces contain energy, but it is lost from that food web.
• Not all organisms are eaten so they may die and they are decomposed.

Question 22

Pyramid of numbers

Answer 22

a graph showing the total number of individual organisms at each level in the food chain of an ecosystem.

Question 23

What happens to the number of organisms at different positions in a food chain?

Answer 23

There are usually more plants than animals and more herbivores than carnivores in a food chain.

Question 24

How can we represent the number of organisms at different positions in a food chain?

Answer 24

We can represent the number of organisms using a pyramid of numbers.

Question 25

Why is there less energy available as you go up the pyramid of energy?

Answer 25

There is less energy available as you go up the pyramid because some energy is lost to the environment.

Question 26

Why are there fewer animals at higher levels of the pyramid of energy?

Answer 26

There are fewer animals higher up the pyramid because less energy is available at each level.

Question 27

What are the problems with pyramid sof numbers?

Answer 27

• Many organisms feed at more than one trophic level. Eg– you are a primary consumer when you eat vegetables, asecondary consumer when you eat meat / drink milk, and a tertiaryconsumer when you eat a predator fish e.g. salmon.
• Doesn’t represent the complexity of food webs

Question 28

Pyramid of biomass

Answer 28

a graph showing the relative quantity of biomass at each trophic level.

Question 29

Why are pyramids of biomass better than pyramids of numbers?

Answer 29

Because pyramids of biomass give a better idea about the quantity of energy at each trophic level than pyramids of numbers.

Question 30

Pyramid of Energy

Answer 30

a graph showing the relative quantity of energy at each trophic level

Question 31

How could scientists calculate the figures for a pyramid of energy?

Answer 31

1. Work out all the links in the food web
2. Take samples of each organism and find out how much energy they contain. (Kill the organism,dry it,burn it to see how much energy is released)
3. Multiply by the number of each organism in that food web

Question 32

Why are pyramids of biomass often used instead of more accurate energy measurements?

Answer 32

Because the data is much easier to collect.

Question 33

Where is the most energy in a food chain?

Answer 33

At the start of the food chain.

Question 34

Why is there more energy at the start of the food chain?

Answer 34

There is more energy at the start of the food chain because less energy has been “lost” between the trophic levels.

Question 35

What type of food provides humans with the most efficient energy and why?

Answer 35

Humans can get the most efficient energy from plant foods like wheat, rice, and potatoes because there is more energy at the start of the food chain. Less has been “lost” between the trophic levels.