Ecology

Question 1

Definition of population

Answer 1

Number of individuals of a species living in a particular habitat at a particular time

Question 2

Definition of community

Answer 2

All of the individuals of all the species living in a certain habitat at a certain time

Question 3

Definition of habitat

Answer 3

Place where an organism lives

Question 4

Definition of ecosystem

Answer 4

All the biotic and abiotic factors that interact with a habitat at one time

Question 5

Definition of biotic factors

Answer 5

Living factors in the ecosystem

Question 6

Definition of abiotic factors

Answer 6

Non-living factors in the ecosystem

Question 7

Examples of biotic factors

Answer 7

Competition, new pathogens, new predator, availability of food (prey), microorganisms

Question 8

Examples of abiotic factors

Answer 8

Wind direction/intensity, light intensity, water availability, mineral ions, moisture level, nitrogen levels

Question 9

Why are food chains usually so short?

Answer 9

Not all energy is passed from one trophic level to the next. Only around10% of the energy at each trophic level is passed onto the next. Total amount of energy available eventually becomes too small to support another trophic level.

Question 9

What causes loss of energy?

Answer 9

Some parts of the organism are inedible so they aren’t eaten (bones, fur).
Some parts of energy are indigestible so egested as faeces.
Energy is lost by excretion (urine).
Heat energy lost by respiration.
Energy lost due to movement.

Question 10

What do the arrows in food chains represent?

Answer 10

Transfer of energy.

Question 10

Can a protoctista be a producer?

Answer 10

Yes, it can photosynthesise.

Question 11

How to estimate the population of an organism using a quadrat?

Answer 11

Calculate area of the habitat. Use 2 tape measures at right angles to make a 10m x 10m set of axes. Use a random number generator to generate pairs of numbers from 1-10. Use these numbers as coordinates and place your quadrat at the coordinates. Measure number of individuals in the quadrat and then repeat 10x (reliable) with different coordinates. Calculate average number of individuals in a quadrat. Calculate how many quadrats (find area of quadrat before) fit in the area of the habitat. Multiple average number of individual in quadrat by how many quadrats fit in the habitat.

Question 12

Limitations of using quadrat

Answer 12

Can be easy to miss individuals, especially when covered by a different species. Identifying species can be tricky.

Question 13

What is a quadrat?

Answer 13

A square frame used to measure abundance of organisms in an area. Usually 50cm x 50cm.

Question 14

Why may using the mean number of organisms not be accurate for calculating the number of organisms in the habitat?

Answer 14

Too few quadrats placed.
Sample may not be representative of lawn.

Question 15

What is nitrogen fixation?

Answer 15

Process of turning Nitrogen gas into ammonia/nitrates by nitrogen fixing bacteria or lightning

Question 16

What is nitrification?

Answer 16

Turns ammonium in decaying matter into nitrates by nitrifying bacteria so it can be absorbed by plants.

Question 17

What is denitrification?

Answer 17

Nitrates are turned back into nitrogen gas by denitrifying bacteria

Question 18

What is decomposition (nitrogen cycle)?

Answer 18

Molecules containing nitrogen such as proteins and urea are broken down by bacteria and fungi. Ammonia is released back into the soil.

Question 19

What type of plants contain nitrogen fixing bacteria?

Answer 19

Roots of legume plants

Question 20

Examples of legume plants

Answer 20

Beans

Question 21

Definition of biodiversity

Answer 21

The variety of living organisms in a particular area, including the range of different species and the genetic variation within those species

Question 22

Describe photosynthesis as a stage of the carbon cycle

Answer 22

Carbon atoms from carbon dioxide become part of glucose molecules (stored as starch in plants)

Question 23

Describe respiration as a stage of the carbon cycle

Answer 23

Some glucose will be broken down by the plant during respiration. Carbon in glucose becomes part of carbon dioxide molecule and is released into the air.

Question 24

Describe decomposition as a stage of the carbon cycle

Answer 24

When plants or animals die, decomposers (bacteria and fungi) feed on them. Carbon becomes part of decomposer's body. When decomposers respire, carbon becomes carbon dioxide and part of the air.

Question 25

Describe combustion as a stage of the carbon cycle

Answer 25

When fossil fuels are combusted/burnt, carbon dioxide is released into the atmosphere.

Question 26

Describe feeding as a stage of the carbon cycle

Answer 26

Some of carbon compounds in plant are eaten by animals. When animals respire, it is released back into the air as carbon dioxide.