Ecology

Question 1

Lost the 4 biotic factors

Answer 1

Food, predators, competition, pathogens

Question 3

Explain how the availability of food (biotic) can affect organisms

Answer 3

If the availability of food falls then the no. of organisms on that community will also fall

Question 4

Explain how a new predator (biotic) can affect organisms

Answer 4

Arrival of a new predator can cause populations of a prey to fall and also affect existing predators that compete for the same prey

Question 5

Explain how a competition (biotic) can affect organisms

Answer 5

If a specie is outcompeted then it’s population can fall so much that the numbers are no longer sufficient to breed - extinct

Question 6

Explain how pathogens (biotic) can affect organisms

Answer 6

If an infectious disease emerges and spreads it can wipe out a population of species

Question 7

What is abiotic and list 6 abiotic factors

Answer 7

Abiotic means non-living
Light intensity, temperature, water, PH and mineral content of soil, wind intensity, Carbon dioxide and oxygen

Question 8

Explain the abiotic factor of light intensity

Answer 8

All plants need light for photosynthesis however if light intensity is too low then the rate of photosynthesis falls and plants grow slower
As a result animals that feed on those plants may not have enough food

Question 9

Explain the abiotic factor of temperature

Answer 9

If the temperature of an environment changes it can cause distribution of species e.g. animals can migrate and plants can disappear

Question 10

Explain the abiotic factor of water availability

Answer 10

All organisms need water to survive however many species are adapted to deal with low levels of water.

Question 11

Explain the abiotic factor of PH and mineral content in soils

Answer 11

Many plants cannot grown on soil that’s too acidic or too alkaline because plants need certain minerals in the soil e.g. nitrate (amino acids for protein)

Question 12

Explain the abiotic factor of wind intensity

Answer 12

Strong winds blowing inland from the sea can cause plants to lose water therefore sand dunes are adapted to reduce water loss

Question 13

What are structural adaptations

Answer 13

Adaptions of body shape or body structures

Question 14

Give 2 example of a structural adaptation of a camel

Answer 14

They have humps of their back which store fat that works as a thermal insulator. By storing fat in one place it allows heat loss from other parts of the camels body reducing water loss
Camels also have long eyelashes to keep dust out of their eyes

Question 15

What are functional adaptations

Answer 15

Adaptions of the body functions of an organisms

Question 16

Give 2 example of a functional adaptation of a camel

Answer 16

Camels produce concentrated urine and dry faeces reducing water loss
Camels can tolerate very large changes in their body temperature helping them cope with intense heat

Question 17

What are behavioural adaptions

Answer 17

Adaptations to animals lifestyle or behaviour

Question 18

Give 1 example of a structural adaptation of a dessert (kangaroo rat) rat

Answer 18

They are nocturnal meaning they avoid the heat at daytime and sleep in burrows underground protecting them of predators

Question 19

Explain how cacti are adapted

Answer 19

Extensive and shallow roots allowing them to catch as much water as possible after rainfall
Also store water in their stem

Question 20

On the food chain : grass-rabbit-fox
List which ones the producer and why

Answer 20

The grass is the producer similarly in the sea algae would be the producer because they synthesise complex molecules like glucose (photosynthesis). Call glucose biomass therefore the producers are the source of all biomass in a community.

Question 21

On the food chain : grass-rabbit-fox
List which ones the primary consumer and why

Answer 21

It is the rabbit because it eats the grass (passes the biomass to the rabbit)

Question 22

On the food chain : grass-rabbit-fox
List which ones the secondary consumer and why

Answer 22

The fox because it eats a primary consumer /rabbit.

Question 23

In this 4 staged food chain : tree- caterpillar- small bird- hawk
What’s the hawk called

Answer 23

The tertiary consumer as it is a bird of prey which eats the secondary consumer

Question 24

What are predators

Answer 24

Consumers that kill and eat other animals

Question 25

In this food chain : grass - rabbit - fox Which ones the predator Which ones the prey

Answer 25

Fox is a predator and rabbit is a prey

Question 26

The numbers of predators and prey rise and fall in cycles Explain in detail using the example of rabbits and foxes (start with an increase in rabbit population)

Answer 26

1. If it is a warm summer and there is plenty of grass for the rabbits to eat this means that the rabbits offspring’s would survive increasing the rabbit population 2. Now foxes have more rabbits to kill and eat so the fox population increases where as the rabbit population now decreases since they will be eaten 3. Because the rabbit population falls the population of foxes would also fall since they have fewer rabbits to kill and eat 4. Due to the number of foxes falling more rabbits will now survive and reproduce so their population increases again

Question 27

What’s a limitation to a predator-prey population cycle

Answer 27

There must be a stable community (biotic and abiotic factors are in balance) otherwise the cycle may change

Question 28

What is random sampling

Answer 28

Sampling done to compare the numbers of organisms in DIFFERENT areas

Question 29

What do we use to do ransom sampling and what is it

Answer 29

A quadrat is a wooden/plastic square which we place on the ground to count the numbers of plants or slow-moving organisms inside it

Question 30

Where are the quadrats placed in random sampling

Answer 30

At random locations across the area, this is done by using random numbers to select different locations

Question 31

What are the first 3 steps of random sampling (practical)

Answer 31

1. Place two tape measures at right angles measuring 20m each 2.Then need one bag it containing the numbers 1 to 20 3. The first student removes a number from the bag (and puts the number back into the bag after reading it) and moves to the point on one tape measure that is equal to the number picked

Question 32

What are steps 4,5,6 of random sampling (after one student moves to a tape measure)

Answer 32

4. Another student then picks a number from the same bag and moves along the other tape measure to where the number equals the tape measure reading 5. Then a students walks to where both students meet and places down a 0.5 by 0.5 quadrat and counts the no. of organisms inside 6. Repeat this about ten times across ten quadrats 7. The students then need to estimate the total population of organism in the field by this equation Total population size = (total area/area sampled) x number of organisms of that specie counted in sample In this sample it would be (400m^2 / 2.5m^2) x number counted

Question 33

Explain why the random sample practice does not represent the whole area

Answer 33

There might he regions within the area with a much higher or lower number of daises than the average If this is the case we should increase the number of quadrats thrown to get a greater percentage of area.

Question 34

Of the practical asks to look at the effect of light intensity on the distribution of daises what do you do

Answer 34

You do systemic sampling using a transect line to see how the number of daises change from the tree out wards by placing a tape measure (transect) at the tree then using a quadrant to count the number of daises at the start of the transect. Also need to record the light intensity using a light meter. Then you move the quadrant 1m down the tape measure and repeat measurements. Should see a greater number of daisies the further away from the tree and st the tree block sunlight which is essential for photosynthesis.

Question 35

When do you do systemic sampling.

Answer 35

If you want to investigate whether the number of species change across a habitat.