Organisation of an ecosystem - done

Question 1

What are producers?

Answer 1

Photosynthetic organisms are the producers of biomass for life on Earth

Question 2

How do producers make their own food?

Answer 2

Using energy from the Sun

Question 3

Producers’ characteristics: (3)

Answer 3

• start of every food chain (the first trophic level, which is always the biggest)
• can photosynthesise and make glucose by photosynthesis
• They use this glucose to produce other biological molecules, which then make up the producer’s biomass

Question 4

What does a food chain show?

Answer 4

the transfer of energy from one organism to the next

Question 5

What is the source of all energy?

Answer 5

light energy from the Sun

Question 6

Main processes of the CO2 cycle?

Answer 6

• combustion = carbon is released into the atmosphere when fossil fuels are burned
• photosynthesis = plants absorb the CO2 to produce glucose
• plants are eaten by animals. They respire and release CO2
• Decomposition = carbon in dead and decaying matter is broken down
• Fossilisation = of dead plants and animals take in CO2 from atmosphere

Question 7

What is evaporation?

Answer 7

Energy from the sun turns water from a liquid to a gas

Question 8

What is transpiration?

Answer 8

Plants allow some water to evaporate from their leaves. This ensures water is continuously pulled up from the soil and travels through the plant to its leaves

Question 9

What is condensation?

Answer 9

When water vapor cools, water turns from a gas into a liquid.

Question 10

What is precipitation?

Answer 10

The falling of rain, snow and sleet from the sky

Question 11

What are the main groups of decomposers?

Answer 11

Bacteria and fungi

Question 12

What do decomposers do?

Answer 12

When living organisms produce waste products or organisms die, the waste products and dead organisms are broken down

Question 13

What affects rate of decay?

Answer 13

Temperature, water and availability of oxygen

Question 14

How does temperature affect the rate of decay?

Answer 14

At warmer temperature, enzymes involved in decomposition can work at faster rate, increasing the rate of decay. If the temperature is too high these enzymes will denature and the rate of decay will decrease
- At low temperatures, the enzymes involved in decomposition work slowly, decreasing the rate of decay

Question 15

How does water affect the rate of decay?

Answer 15

Decomposers require water to survive. Many decomposers also function by secreting enzymes onto decaying biological matter and absorbing the products of this chemical digestion - without water these reactions cannot occur
WATER AVAILABILITY DECREASES, RATE OF DECAY DECREASES

Question 16

How does availability of oxygen affect the rate of decay?

Answer 16

Oxygen is needed by decomposers for aerobic respiration - without oxygen, they cannot survive. For these decomposers, the rate of decay decreases as oxygen decreases.
- Some can respire anaerobically resulting in anaerobic decay

Question 17

What does anaerobic decay produce?

Answer 17

methane gas (as well as carbon dioxide). Together these products are given the term ‘biogas’

Question 18

What are biogas generators?

Answer 18

Large containers in which animal or plant waste is allowed to decay anaerobically. Can be used to produce methane gas as fuel.

Question 19

Decay on fresh milk experiment steps:

Answer 19

1. Half fill beakers with hot water from kettle and cold water until desired temperature is reached
2. Label 4 test tubes - 3 milk, 1 lipase
3. In the lipase tube add 10cm of lipase solution. Use a 5cm3 syringe to add 2.5cm3 of milk to each of the milk test tubes
4. In milk test tube add 3 drops of cresol red solution
5. Using another 5cm3 syringe add 1.5cm3 of sodium carbonate solution to each milk test tube
6. Put thermometer in a milk test tube
7. Put test tubes in water bath and wait until contents reach the same temp
8. Transfer 2cm3 of lipase solution with a pipette into the test tube
9. Start stopwatch and stir until their is a colour change. Record time
10. Repeat step with different temperatures

Question 20

Why does the milk’s pH reduce as it decays?

Answer 20

This is because bacteria present in milk carry out a chemical process to provide them with energy. This process converts lactose sugar in the milk to lactic acid, and producing this acid reduces the pH of the milk.

Question 21

Examples of changing environmental factors that can affect the distribution of organisms include: (3)

Answer 21

• Temperature
• Availability of water
• Composition of atmospheric gases

Question 22

Human activities that are reducing biodiversity in ecosystems: (3)

Answer 22

• Producing waste, landfill and toxic chemicals
• Deforestation
• Global warming (lead to flooding and extreme weather events)

Question 23

Ways humans rely on many other species to survive: (3)

Answer 23

• Photosynthetic organisms to produce oxygen, without which we cannot respire
• Pollinator species such as bees to pollinate our food crops
• Plant species for medicine

Question 24

Effects of rapid human population growth?

Answer 24

• More resources are used to sustain the growing human population
• More waste is produced
• More pollution is created