B18 - Organisms And Their Environment

Question 1

Principal source of energy input into biological systems

Answer 1

Sun

Question 2

Process that converts light energy into chemical energy

Answer 2

the producer (a plant) uses photosynthesis to convert the light energy to chemical energy

Question 3

What do arrows symbolise in a food chain or web

Answer 3

Energy flow/transfer

Question 4

Food web

Answer 4

A network of interconnected chains

Question 5

Producer + trophic level + position

Answer 5

• An organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis
• T1
• producer

Question 6

Consumer + trophic level + position

Answer 6

• An organism that gets its energy by feeding on other organisms
• T2, T3, T4 - possibly more
• primary, secondary tertiary

Question 7

Herbivore

Answer 7

An animal that gets its energy by eating plants

Question 8

Carnivore

Answer 8

An animal that gets its energy by eating other animals

Question 9

Decomposer

Answer 9

An organism that gets its energy from dead or waste organic material

Question 10

Answer structure when talking about affects on food chain

Answer 10

1 - above
2 - below

Question 11

Trophic level

Answer 11

The position of an organism in a food chain and food web

Question 12

What happens to energy when it gets passed on from one organism to another

Answer 12

About 90% is lost

Question 13

Why isn’t 100% of energy passed on

Answer 13

• consumers dont eat everything - e.g bones, teeth, roots
• as organisms respire they lose heat energy and it goes back into the environment
• egestion and excretion

Question 14

Why is there usually no more than 5 trophic levels

Answer 14

• energy is lost at each trophic level
• so there is not enough energy left to support organisms at higher levels

Question 15

Efficiency of energy transfer formula

Answer 15

Efficiency = energy transferred to next level/energy recieved from previous level * 100

Question 16

Decomposition/decay

Answer 16

The breakdown of organic matter (dead organisms or waste material)

Question 17

Overharvesting - e.g overgrazing or overfishing impact (3)

Answer 17

• decrease in biodiversity
• risk of extinction of a species
• disrupts natural food chain of habitat

Question 18

Introducing foreign species impact

Answer 18

• disrupts natural food chain
• competes with existing species for resources
• could cause native species to migrate
• no natural predators to control
• could introduce disease
• could reduce biodiversity
• could cause extinction of other species

Question 19

Why is it more efficient for humans to be vegetarian

Answer 19

• energy is lost at each trophic level
• plants are lower down the food chain and so less energy has been lost
• so its a lot more efficient for humans to eat plants than animals