B15

Question 1

Sun’s role in ecosystems/communities

Answer 1

The Sun is the source of energy that is transferred through ecosystems with the chemical bonds that make up organisms

Question 2

Examples of interdependence
in a community

Answer 2

Plants produce food by photosynthesis
Animals eat plants
Animals pollinate plants
Animals eat other animals
Animals use plant and animal materials to build nests and shelters
Plants need the nutrients from animal droppings and decay

Question 3

Examples of stable communities

Answer 3

Tropical rainforests
Ancient oak woodlands
Mature coral reefs

Question 4

Can a stable community be replaced?

Answer 4

No

Question 5

How does light intensity affect communities?

Answer 5

Plants need light to grow well
and the breeding cycles of plants and animals are linked to light intensity

Question 6

How does temperature affect communities?

Answer 6

Temperature is a limiting factor on photosynthesis, so also affects growth of plants,
which affects the number of herbivores and carnivores than can survive in the community

Question 7

How do moisture levels affect communities?

Answer 7

Plant growth is greatest when water is available and animals eat these plants, so without water there is little/no life

Question 8

How does soil PH and mineral content affect communities?

Answer 8

Plants struggle to grow in areas with low mineral ions and a low soil PH hinders decay(release of mineral ions back into the soil).

Question 9

How does wind intensity/direction affect communities?

Answer 9

Strong prevailing winds affect the shape of trees/the landscape and cause plants to transpire(lose water) fast

Question 10

How does availability of oxygen affect communities?

Answer 10

Water-living organisms need a high level of dissolved oxygen.

Question 11

How does availability of CO2 affect communities?

Answer 11

CO2 acts as a limiting factor for photosynthesis and plant growth and can affect distribution of animals(attracts mosquitoes)

Question 12

How does availability of food affect communities?

Answer 12

When there’s lots of food, organisms breed successfully but organisms can’t survive without food.

Question 13

How do pathogens/parasites affect communities?

Answer 13

When a pathogen/parasite emerges, organisms have no resistance to the disease
and a pathogen can wipe out a population in a community.

Question 14

How does interspecific competition affect communities?

Answer 14

A new species may outcompete another to the point the numbers are too low for successful breeding

Question 15

How are plants adapted to low light levels?

Answer 15

Plants may have more chlorophyll or bigger leaves.
Nettles in the shade of other bushes have a greater surface area than nettles in the open.

Question 16

How are plants adapted to low mineral content?

Answer 16

Carniverous plants like sundew trap and digest animal prey when nitrate levels are low.

Question 17

How are plants adapted to a low availability of oxygen?

Answer 17

Invertebrates survive in water with low oxygen levels.

Question 18

Ecology

Answer 18

How living and non-living factors affect the abundance and distribution of organisms

Question 19

Quadrat

Answer 19

A sample area marked out by a square frame used to count the number of organisms. You use the same size quadrat each time to make the results valid

Question 20

How must you choose your sample areas?

Answer 20

At random - to ensure your results reflect the true distribution of organisms and conclusions you make are valid e.g. person with quadrat closes their eyes, spins round, opens their eyes and walks 10 paces before dropping the quadrat

Question 21

Quantitative sampling

Answer 21

After taking several random readings at regular time intervals, find the mean number of organisms per m2/quadrat.
You can also find the range of distribution and median/mode of the data.

Question 22

How to use a transect

Answer 22

Stretching a tape between two points, sample organisms along the line at regular intervals using a quadrat to show how the distribution of organisms changes along that line

Question 23

Examples of competition for food

Answer 23

Herbivores feed for plants, the animals eating a wide range of plants are likely to be more successful
Carnivores compete for play, predators with long legs for running fast and sharp eyes
to spot prey are successful
Prey compete with each other to avoid being caught, some animals contain poisons and warning colours so predators know which animals to avoid

Question 24

Competition for territory

Answer 24

Territory could simply be a place to build a nest, or the space for an animal to find food and reproduce.
Animals use urine or faeces to mark the boundaries of their territories

Question 25

Competition for a mate

Answer 25

In some species, males fight and the winner gets to mate with the female.
Peacocks have tail feathers to attract females, male lizards have bright colours to attract females

Question 26

How are big, tall plants adapted?

Answer 26

Take up water and nutrients from the soil, as well as reducing amount of light reaching the plants beneath them

Question 27

How plants cope with competition?

Answer 27

Small plants in woodlands grow early in the year, when lots of sunlight is available
Plants use minerals from leaves from other trees that rot in the autumn to flower, make seeds and die before trees get full leaf again
Different roots: Some plants have shallow roots taking water and nutrients from near the surface of the soil, while some plants have long, deep roots that go far underground
Plants have tendrils or suckers
that allow them to grow taller than other plants to reach light
Plants grow leaves with a bigger surface area to take advantage of light

Question 28

How plants spread the seeds

Answer 28

To reproduce, plants have to reduce competition with its own seedlings, so use the wind to spread their seeds far,
using explosive seed pods/animals and fruit or seeds adapted to flight

Question 29

What do plants need to survive?

Answer 29

Light, CO2, water, oxygen and minerals to produce glucose to produce energy to survive

Question 30

What do animals need to survive?

Answer 30

Food from other living organisms, water and oxygen

Question 31

What do microrganisms need to survive?

Answer 31

A range of things

Question 32

Plant adaptations

Answer 32

They get water and mineral ions from the soil through their roots
Epiphytes live high above the ground attached to other plants, collecting water and nutrients from the air and in specially adapted leaves
The saguaro cactus plants open at night and stand on top of the cactus for bats to feed on, pollen is transferred from one flower to another using the bat’s fue

Question 33

Animal adaptations

Answer 33

Herbivores have teeth for grinding up plant cells
Carnivores have teeth for tearing flesh or crushing bones

Question 34

Adaptations in the environment

Answer 34

Sea birds cry salty tears from a salt gland to get rid of the extra salt they get from salt water
Animals and plants produce a chemical in a cell that stops water in the cells freezing and destroying the cells
Plants like water lilies have air spaces in their leaves and float on top of the water to photosynthesise.

Question 35

Adaptations of extremophiles

Answer 35

Some live at very high temperatures, bacteria called
thermophiles survive at temperatures above 45-80C and have enzymes to not denature at these high temperatures
Some extremophile bacteria like the Dead Sea and salt flats can live in salty conditions with adaptations to the cytoplasm so water doesn’t move out of their cells into the salty environment by osmosis

Question 36

Examples of structural adaptations

Answer 36

The shape/colour of the organism
Camouflage - ensures predators and prey can’t be seen by each other
Large ears for organisms to transfer energy to the surroundings, cooling them down

Question 37

Examples of behavioural adaptations

Answer 37

Migration to move to a better climate
Basking to absorb energyy from the sun
Tool-using to obtain food

Question 38

Examples of functional adaptations

Answer 38

Reproduction
Metabolism
Delayed implantation of embryos
In the kidneys to produce concentrated urine so you don’t need to drink in a desert

Question 39

How does surface area to volume ratio affect body temperatures?

Answer 39

The smaller the surface area to volume ratio the easier it is to reduce energy transfer to the environment and minimise cooling

Question 40

Plant adaptations

Answer 40

Plants in a dry environment have curled leaves to reduce the surface area of a leaf trapping a layer of moist air around the leaf to reduce the amount of water the plant loses by evaporation(e.g. marram grass)
Desert plants have small fleshy leaves with a thick cuticle to keep water loss down
Butcher’ broom has flattened leaves, stems have less stomata than true leaves so plant loses little water
Extensive root systems to collect water
Fleshy leaves/stems/roots store water

Question 41

Counter current exchange system

Answer 41

Penguins and other arctic animals have a special blood flow system to their feet called the counter current exchange system.
1) The cold blood from the foot returns to the penguin’s body in the vein.
2) This blood runs very closely to the warm blood in the artery taking blood to the foot.
3) The cool blood is warmed by the warm blood

Question 42

Carrion

Answer 42

Decaying flesh and tissue of dead animals

Question 43

Scavengers

Answer 43

Organisms feeding on dead animals(carrion)

Question 44

Mutualism

Answer 44

When both species benefit from a relationship

Question 45

Parasitism

Answer 45

When a parasite only benefits from living on the host

Question 46

Sampling techniques(required practical)

Answer 46

1) Line transects
2) Sweep net
3) Using quadrats
4) Pitfall trap