B1.5 + 6 Energy and Biomass in food chains + Waste materials from plants and Animals

Question 1

Define ‘biomass’

Answer 1

The dry mass of biological material in living organisms

Question 2

Define ‘photosynthesis’

Answer 2

The process that transfers light energy to chemical energy which can be stored in the substances that make up the plant’s cells

Question 3

What is the source of energy for most communities of organisms?

Answer 3

Radiation from the Sun.

Question 4

What absorbs a small amount of radiation from the sun?

Answer 4

• Green plants

- Algae

Question 5

What does a pyramid of biomass show?

Answer 5

The mass of living material of all organisms at each stage of the food chain

Question 6

Explain the ways that the amounts of material and energy are reduced at each stage of the food chain. (6)

Answer 6

• Some material/energy is lost in waste materials
• Some energy is lost during respiration (life processes e.g movement increase this)
• Some energy is transferred as heat to its surroundings
• Some energy is lost in maintenance and repair
• Not all the organism will be eaten (e.g bones contain energy)
• Not every single organism will be eaten (some will die of natural causes)
• Decomposers break down animals that die of natural causes, taking their energy.

Question 7

Why is decay important for the soil?

Answer 7

It ensures mineral ions (and other substances plants need to grow) are returned to it

Question 8

How are materials that living things remove from the environment for growth returned to the environment? (2)

Answer 8

• Waste materials

- Death and decay

Question 9

What conditions do microorganisms work best in?

Answer 9

• Warm
• Moist
• Plenty of oxygen

Question 10

How are materials constantly recycled in a stable community?

Answer 10

The processes removing materials are balanced by processes returning materials

Question 11

Define the ‘carbon cycle’

Answer 11

The continuing recycling of carbon between living things and the environment

Question 12

Why is the carbon cycle important?

Answer 12

All living things require carbon

Question 13

Explain the carbon cycle.

Answer 13

• Carbon dioxide is removed from the atmosphere by photosynthesis - the carbon is used to make carbohydrates, fats and proteins in the plants and algae.
• Some of the carbon is returned as CO2 to the atmosphere when the plants/algae respire.
• Some of the carbon moves through the food chain as animals eat plants and the carbon becomes part of their protein and fat - it is then returned as CO2 when the animals respire.
• Animals produce waste, this as well as their bodies when they die is fed on by detritus feeders which respire and release CO2
• Combustion: food and fossil fuels are burnt, releasing CO2