Section 9 - Ecosystems And Material Cycles

Question 1

What does a producer in the food chain do ?

Answer 1

Produce food in from of glucose, which is converted into complex carbohydrates, proteins and fats by photosynthesis.

Question 2

What does the direction of the arrow in a food chain show?

Answer 2

The direction energy is flowing

Question 3

What is the first organism in a food chain called?

Answer 3

A producer (Tropic level 1)

Question 4

What is the second organism in the food chain called (the one that eats the producer)

Answer 4

A primary consumer (tropic level 2: herbivore)

Question 5

What is the third organism in the food chain called? (The one that eats the primary consumer)

Answer 5

A secondary consumer (tropic level 3: carnivore)

Question 6

What happens if one thing in the food chain is affected?

Answer 6

The rest of the food chain will be affected. Knock on effect.

Question 7

How is energy transferred between animals and plants when they eat one another?

Answer 7

The animal gets the protein, fats and carbohydrates from the animal’s biomass

Question 8

What is an abiotic factor?

Answer 8

A non-living factor

Question 9

What is an biotic factor?

Answer 9

A living factor

Question 10

Name 5 abiotic factors

Answer 10

Choose from: Moisture level, light intensity, temperature, carbon dioxide, wind intensity and direction, oxygen levels & soil acidity and mineral availability.

Question 11

Name at 5 biotic factors

Answer 11

New predators, competition, new pathogens/parasites, availability of food, mutualism.

Question 12

What is the predator prey cycle?

Answer 12

A graph to show the population between two or more animals that affect each other over a period of time

Question 13

Define population

Answer 13

All organisms of one species in a habitat

Question 14

Define community

Answer 14

All organisms of different species in a habitat

Question 15

Define ecosystem

Answer 15

Organisms living along with abiotic conditions

Question 16

Define mutualism

Answer 16

A relationship where both organisms benefit

Question 17

Define parasites

Answer 17

When one organism uses the other for food and shelter but the other organism doesn’t benefit

Question 18

What is a quadratic?

Answer 18

A square frame in losing a known area

Question 19

What do you use a quadratic for?

Answer 19

To compare abundance

Question 20

How would use measure abundance with a quadratic?

Answer 20

1) randomly place quadratic on the ground
2) count the organisms in the quadratic
3) repeat steps 1&2 many times
4) work out the mean number of organisms in the quadrats
5) repeat steps 1-4 in a different area
6) compared the means of the two samples

Question 21

What’s the equation for estimating the population size ?

Answer 21

Mean of organisms per m(2) x total area of habitat

Question 22

Explain the method to measure distribution

Answer 22

1) mark out a line of the area you’re studying (belt transfer)
2) place quadrats along the line at regularly spaced intervals and collected the data
3) record several factors in the area (ie. light intensity, pH of soil)
4) find the mean no. of organisms that you just collected
5) plot a graph to see if there’s a correlated change in abiotic factors and distribution

Question 23

Define biodiversity

Answer 23

Variety of living organisms in an ecosystem

Question 24

Define eutrophication

Answer 24

The addition of more nutrients to an ecosystem than it normally has

Question 25

Explain the process of eutrophication

Answer 25

1) fertiliser dissolves in water in the soil
2) if plants don’t absorb the nitrates (from the fertiliser) some get into near by water. Heavy rainfall can cause run-off into water
3) nitrates cause eutrophication in the water
4) the added nitrates cause the algae and plants in the water to grow rapidly. The surface algae shades out the plants below, which die due to lack of sunlight
5) decomposers/bacteria break down the dead plants and take oxygen from the water for respiration
6) Now there’s too little oxygen in the water for fish, causing their death because they can’t respire

Question 26

Explain how fish farming can reduce biodiversity in surrounding areas

Answer 26

1) food is added to the nets to feed the fish which produces waste, this leaks into the open water and causes eutrophication which leads the the death of wild species
2) fish farms are in open water, breeding ground for large number of parasites. These can then get out and harm and infect other wild animals
3) predators are attracted to the nets and get trapped in them and die
4) farmed fish could escape into the wild, causes problems for wild populations with indigenous species

Question 27

How can the introduction if indigenous species reduce biodiversity?

Answer 27

Non-indigenous (ni) compete with indigenous species for resources and sometimes the ni are better at getting them, out competing the indigenous which will decrease in number and eventually die out.
ALSO no could bring new diseases into the habitat and infect and indigenous species

Question 28

Describe the water cycle

Answer 28

Energy from the sun EVAPORATES water from the land and sea turning it into WATER VAPOUR.
Warm water vapour is carried upwards, when it gets cooler it CONDENSES to form clouds.
Water falls from clouds as PRECIPITATION onto the land, where it provides fresh water.
Drains into the sea and starts again.

Question 29

Why do droughts occur?

Answer 29

When there isn’t enough precipitation

Question 30

What is potable water?

Answer 30

Drinkable water

Question 31

Name two methods of producing potable water from salt water

Answer 31

Desalination and reverse osmosis

Question 32

Describe desalination and its process

Answer 32

It removes salts from salt water.
Water in boiled in a large enclosed vessel so the water EVAPORATES.
The steam rises to the top and the salts stay at the bottom.
The steam the runs down from the top of the vessel and CONDENSES into pure water.

Question 33

What is osmosis?

Answer 33

The net movement of water across a partially permeable membrane from an area of HIGH water concentration to LOW water concentration (lower salt concentration to higher salt concentration)

Question 34

Describe and explain reverse osmosis and its method

Answer 34

It reverses the process of osmosis to get rid of impurities in water.
Salt water is treated to remove solids, before being fed at a very high pressure into a vessel containing a partially permeable membrane.
The pressure causes water molecules to move in the opposite direction to osmosis- so it goes from a higher salt concentration to a lower salt concentration.
As the water is forced through the membrane the salts are left behind, removing them from the water.

Question 35

How much of the atmosphere is made up from nitrogen gas?

Answer 35

78%

Question 36

How can farmers increase the amount of nitrates in their soil?

Answer 36

Crop rotation or fertilisers

Question 37

What is crop rotation?

Answer 37

Where instead of growing the same crop in the same field each year, different crops are grown in a cycle.
The cycle includes nitrogen fixing bacteria plants (eg peas, alfalfa and beans) which helps put nitrates back into the soil (comes from their nodules) for another crop to use the following year.

Question 38

How do fertilisers increase the amount of nitrates in the soil?

Answer 38

By spreading animal manure or compost on the fields, it recycles the nutrients left in the waste and returns then to the soil through DECOMPOSITION.
Artificial fertilisers containing nitrates can also be used p, but they’re expensive

Question 39

What form of nitrogen can the plants use?

Answer 39

Nitrates

Question 40

What does a plant use nitrogen for?

Answer 40

Making proteins

Question 41

How does nitrogen get from plants to animals?

Answer 41

It’s passed along the food chain in forms of protein when the animals eat the plants

Question 42

What do decomposers do ?

Answer 42

Break down proteins (turns complex compounds into simple compounds) in rotting plants, animals and urea.
This then returns the nitrogen to the soil so the nitrogen in the organisms is recycled

Question 43

What is nitrogen-fixation?

Answer 43

The process of turning nitrogen gas in the air into nitrogen containing ions in the soil which plants can use.

Question 44

What are the two main ways nitrogen fixation happens?

Answer 44

Lightning - enough energy in bolt to react nitrogen with oxygen to give nitrates
Nitrogen-fixing bacteria - turn atmospheric nitrogen gas into ammonia which forms ammonium ions

Question 45

Name the four different types of bacteria involved in the nitrogen cycle

Answer 45

Decomposers, nitrifying bacteria, nitrogen-fixing bacteria and denitrifying bacteria

Question 46

What does nitrifying bacteria do?

Answer 46

Turns ammonia in decaying matter into nitrites and then into nitrates

Question 47

What does denitrifying bacteria do?

Answer 47

Turn nitrates back into nitrogen gas

Question 48

Where can you find nitrogen-fixing bacteria?

Answer 48

In the soil and in nodules on the roots of legume plants.

Question 49

Explain how nitrogen-fixing bacteria works with nodules

Answer 49

When the plant decomposes, the nitrogen stored in their nodules is returned to the soil.
Nitrogen ions also leak out during nodule growth

Question 50

Describe the relationship between plants and bacteria and explain why

Answer 50

Mutualistic relationship.

The bacteria gets food (sugars) from the plant and the plant gets nitrogen ions from the bacteria to make proteins

Question 51

Explain how materials are recycled through both biotic and abiotic components of ecosystems

Answer 51

1) living things are made of elements they take from the environment (eg. Carbon, oxygen and nitrogen)
2) they turn these elements into complex compounds (carbs, fats, proteins) that make up living organisms. Elements are passed along food chains when animals eat the plants and each other
3) the elements are recycled, the waste products and dead organisms are broken down by decomposers and the elements are returned to the soil or air.

Question 52

What is the whole carbon cycle ‘powered’ by?

Answer 52

Photosynthesis (green plants use the CO2 to make carbs, fats and proteins)

Question 53

Explain the carbon cycle

Answer 53

1) eating passes carbon compounds in the plant along to animals in a food chain
2) both plant and animal respiration while organisms are alive relaxes CO2 back into the air
3) plants and animals die and decompose, turned into useful products
4) when the plants and animals are broken down by micro organisms, the decomposers release CO2 into the air by respiration as they break down the material
5) useful plant and animal products are burned and release CO2 back into the air
6) decomposition of materials means habitats can be maintained for organisms that live there, eg. Nutrients are returned to the soil and waste material doesn’t pile up.