Ecology

Question 1

Factors which organisms compete for in a given habitat

Answer 1

Plants - light, space, water and mineral ions(nutrients) from the soil
Animals - Space(territory), food, water and mates

Question 2

How are organisms adapted to the conditions that they live in

Answer 2

• Features of their body structure e.g. shape or colour - A camel has a large surface area to volume ratio to help them lose heat
• Behaviour - birds migrating to warmer climates
• Functional - Desert animals conserve water by producing very little sweat

Question 3

Define an ecosystem

Answer 3

The interaction if a community if living organisms with the non living parts of their environments

Question 4

Define interdependence

Answer 4

This means that all the organisms in an ecosystem are dependent upon each other

Question 5

What is a stable community

Answer 5

A stable community is one in which the size of the populations of all species remain relatively constant over time

Question 6

Explain how a change in the abiotic factors would affect a given community

Answer 6

These changes can affect the sizes of population in a community. This means they can also affect the population sizes of other organisms that depend on them. For example, animals depend on plants for food so a decrease in a plant population could affect the animal species in a community.

Question 7

List abiotic factors

Answer 7

• Moisture levels
• Light intensity
• Temperature
• CO2 levels for plants
• O2 levels for aquatic animals

Question 8

Explain how a change in the biotic factors would affect a given community

Answer 8

A change in the environment could be the introduction of a new biotic factor .e.g. a new predator or pathogen. These changes can affect the sizes of populations in a community which can have knock on effects because of interdependence.

Question 9

List biotic factors

Answer 9

• New predators arriving
• Competition
• New pathogens
• Availability of food

Question 10

Describe an extremophile

Answer 10

An extremophile is an organism that lives in an extreme environment. An extreme environment is one in which most organisms would find it difficult or impossible to survive.

Question 11

What is a producer

Answer 11

Starting point of a food chain
Called a producer as they make their own food by photosynthesis

Question 12

What is a primary consumer

Answer 12

Herbivores that eat the plants and algae

Question 13

What is a secondary consumer

Answer 13

Carnivores that eat the primary consumers

Question 14

What is a tertiary consumer

Answer 14

Carnivores that eat other carnivores are tertiary. Carnvivore’s that have no predators are at the top of the food chain so they’re always in the highest trophic level are known as apex predators

Question 15

Explain why, in a stable community, the numbers of predators and prey rise and fall in cycles

Answer 15

The number of predators increases because there are more prey, so there is more food for them to eat. The number of prey reduces because there are more predators, so more get eaten. The number of predators reduces because there is less prey, so less food.

Question 16

Recall the carbon cycle

Question 17

Explain the role of microorganisms in cycling materials through an ecosystem

Answer 17

Microorganisms are responsible for the degradation of organic matter, which controls the release of plant nutrients, but is also important for the maintenance of soil structure and sustainability of soil quality for plant growth.

Question 18

State factors which affect the rate of decay(biology only)

Answer 18

• Temperature
• Water availability
• Oxygen availability
• Number of Decay organisms

Question 19

State the role of decomposers

Answer 19

Decomposers secrete enzymes into the environment. The enzymes digest dead animals or plant material into small, soluble molecules, The small soluble food molecules then diffuse back into the decomposer. The decomposer uses the soluble, food molecules for growth and respiration

Question 20

List the tropic levels

Answer 20

Producers, primary consumers, secondary consumers and tertiary consumers

Question 21

How much biomass gets transferred to the next level

Answer 21

Approximately 0%

Question 22

Reasons for the loss of biomass at each level

Answer 22

• Organisms don’t eat every part of the organism that they are consuming ( the bones) so not all the biomass could be passed on
• Organisms don’t absorb all the stuff in the food they ingest. The things they don’t absorb is egested as faeces
• Some of the biomass is converted into other substances that are lost as waste. For example, organisms use a lot of glucose, obtained from the biomass, in respiration to provide energy for movement and keeping warm, rather than to make more biomass. This process produces lots of waste CO2 and water as by products. Urea is another waste substance that is released in urine with water when the proteins in the biomass are broken down.