Unit 4^ Ecology + Environment

Question 1

Habitat

Answer 1

place where organism lives

Question 2

Population

Answer 2

all organisms of one species in a habitat

Question 3

Community

Answer 3

Is all the different species in a habitat

Question 4

Ecosystem

Answer 4

all organisms living in a particular area and all the abiotic conditions they’re exposed to

Question 5

Biodiversity

Answer 5

the variety of different species of organisms within an ecosystem

Question 6

Abiotic

Answer 6

Non living

Question 7

Biotic

Answer 7

Living

Question 8

What is meant by the word INTERDEPENDENT when describing a food web

Answer 8

That if 1 species changes it affects all the others

Question 9

Hydroponics

Answer 9

Crops grown with their roots in a solution of mineral ions rather than soil

Question 10

Producers

Answer 10

Plants which photosynthesise to produce food

Question 11

Consumers

Answer 11

Animals that eat plants or other animals

Question 12

Decomposers

Answer 12

Organisms that break down dead material + help to recycle nutrients

Question 13

Explain how the use of fertilisers contributes to algal bloom

Answer 13

• fertilisers contain minerals like nitrates
• when it rains these leach into waters which causes EUTROPHICATION (elevated levels of nitrates in water)
• which causes ALGAL BLOOM which is a layer of algae which cover the surface of the water which absorb O2 + block sunlight

Question 14

Explain how the algal bloom causes anaerobic bacteria thrive + aerobic ones to die

Answer 14

• algal bloom is caused by fertilisers which cause elevated levels of nitrates in water = eutrophication
• this algae absorbs o2 + blocks sunlight= many plant die cos of lack of sunlight this increases the dead organic matter which will decompose
• once the nitrate has ran out the algae will also die, also increasing dead organic matter
• the decomposing matter uses o2 + o2 levels drop
• aerobic organisms die + anaerobic thrive cos of lack of O2

Question 15

Design an experiment to investigate the population size in 2 diff areas

Answer 15

• pick 2 areas
• generate random coordinates + lay out measuring tape on field to form x & y axis
• find coordinates and place Quadrat
• count organisms within Quadrat (the ones ur interested in)
• repeat for each coordinate
• calculate mean = number of organisms : number of Quadrats
• repeat for second field + compare results

Question 16

What are the limitations of the Quadrat experiment

Answer 16

Sample is representative

Person could still be biased when placing Quadrat

Quadrat counted INACCURATELY

Question 17

What do the arrows in a good chain represent

Answer 17

Transfer of energy

Question 18

Why is not all the energy in a trophic level passed on to the next trophic level (give 3 reasons)

Answer 18

• some parts of food not eaten or INDIGESTIBLE (bone)
• used up for RESPIRATION
• transferred to surroundings by HEAT

Question 19

Why do we need biodiversity

Answer 19

High biodiversity makes sure ecosystems r stable cos organisms depend on each other for

• shelter + food
• physical environment (pH of soil)

Question 20

What causes the environment to change all the time

Answer 20

Abiotic + biotic factors

Question 21

Give examples of ABIOTIC factors that change an environment

Answer 21

• environmental condits

• pH of soil
• light intensity

•toxic chemicals:

• pesticides (cause bioaccumulation)
• fertilisers (cause eutrophication)

Question 22

Give examples of BIOTIC factors that change the environment

Answer 22

🍐 availability of food

🦈number of predators

🐉competition

Question 23

What do pyramids of biomass show and what shape must they always have

Answer 23

Always have pyramid shape

Biomass = population size x mass of individual

pyramids of biomass show the mass of living material at each stage of the food chain

Question 24

What do food webs show

Answer 24

Food webs show how food chains r linked

INTERDEPENDENT = if 1 species changes it effect all the others

Question 25

Describe the carbon cycle (5 marks)

Answer 25

🌱 plants use carbon from co2 to make carbohydrates, lipids + proteins

🐄 animals eat plants which passes carbon along food chains

🔥respiration by living things releases co2 back into the air

🦴 animals + plants die = go into soil where they’re broken down by ..

💀DECOMPOSERS which use enzymes to break down the dead material using it for respiration (co2 released)

✈️fossil fuels are burnt by humans =combustion releases co2

Question 26

What percentage of energy available becomes biomass?

Answer 26

Only 10% of the total energy available becomes biomass