Chapter 7 - Ecology

Question 1

What is a population ?

Answer 1

the number of organisms of the same species living in the same area.

Question 2

What is a habitat ?

Answer 2

The area where a population lives

Question 3

What is a community ?

Answer 3

Where several different populations are found living close together.

Question 4

What is an abiotic factor ?

Answer 4

A non-living factor

Question 5

What is a biotic factor ?

Answer 5

A living factor

Question 6

What piece of equiptment is used for sampling ?

Answer 6

A quadrat

Question 7

How do you obtain reliable results in fieldwork ?

Answer 7

• sample needs to be as large as possible
• samples taken at rando locations within the habitat
• repeat and average

Question 8

How would you measure plant distribution ?

Answer 8

Use percentage cover (usually round up to the nearest 10%)

Question 9

How can wind affect the distribution of plants and animals ?

Answer 9

Can be measured using anemometers. Can affect distribution in exposed areas e.g sand dunes

Question 10

How can water affect the distribution of plants and animals ?

Answer 10

soil moistures can be found by weighing them then drying them out and the difference in the two weights was the water.

Question 11

How can pH affect the distribution of plants and animals ?

Answer 11

It can be measured using test kits or probes. Some plants will only grow in acidic/alkaline soils.

Question 12

How can light affect the distribution of plants and animals ?

Answer 12

Can be measured using light meters. All plants need light to photosynthesise.

Question 13

How can temperature affect the distribution of plants and animals ?

Answer 13

Can be measured using a thermometer.

Question 14

what does the term biodiversity mean ?

Answer 14

a measure of the different species living in an area

Question 15

Where does all the energy in our food webs come from ?

Answer 15

All the energy comes from the sun and is trapped by green plants (producers)

Question 16

What do the arrows on a food web represent ?

Answer 16

transfer of energy through the food web

Question 17

Why are food webs always not 100% efficient ?

Answer 17

Due to respiration, excretion, egestion and uneaten parts of the animal

Question 18

Why are shorter food chains more efficient ?

Answer 18

Because less energy is lost between trophic levels

Question 19

What are the advantages/disadvantages of a pyramid of biomass ?

Answer 19

Advantages: more accurate to show the relationships in a community

Disadvantages: Harder to get value for biomass

Question 20

What are the disadvantages/advantages for a pyramid of numbers ?

Answer 20

Advantages: Easy to obtain value for number

Disadvantage : Can be misleading (tree = 1 but is 100 kg insect = 1 but is 1 g)

Question 21

What is the name for bacteria that secrete enzymes ?

Answer 21

saprophytic

Question 22

How do saprophytic break down organisms ?

Answer 22

They secrete enzymes onto the soil or dead organism. The enzyme breaks it down and then the bacteria absorb it.

Question 23

How is humus formed ?

Answer 23

It’s formed from decomposing plant and animal material

Question 24

What are the three optimum features for the rate of decomposition ?

Answer 24

• a warm temperature
• adequate moisture
• a large SA in the decomposing organism

Question 25

How is photosynthesis involved in the carbon cycle ?

Answer 25

carbon dioxide is taken up by plants

Question 26

How is feeding involved in the carbon cycle ?

Answer 26

animals eat plants and the carbon built up in the organic compounds is passed on

Question 27

How is respiration involved in the carbon cycle ?

Answer 27

When anything respires they return carbon back to the atmosphere as CO2

Question 28

How is decomposition involved in the carbon cycle ?

Answer 28

The decomposers gain carbon from decomposing dead organisms. They return carbon by respiration

Question 29

How is fossilisation involved in the carbon cycle ?

Answer 29

The dead organism does not decay. Theses fossils can eventually turn into fossil fuels.

Question 30

How is combustion involved in the carbon cycle ?

Answer 30

When fossil fuels are burned they release Carbon back into the atmosphere

Question 31

What are the problems of global warming ?

Answer 31

- increasing temperatures (melting ice caps) - increasing frequency of extreme weather - loss of habitats

Question 32

What are the two main causes of global warming ?

Answer 32

Deforestation and burning fossil fuels.

Question 33

Explain nitrification :

Answer 33

Plants absorb nitrogen as nitrates to from proteins. They are eaten. Eventually the nitrogen is returned to the ground as urine or death and decay. A special group of bacteria convert ammonia to nitrates in the soil.

Question 34

Explain Nitrogen fixing bacteria :

Answer 34

The bacteria gain carbohydrates from the legumes and they provide a source of nitrates. the process of converting nitrogen from the atmosphere into nitrates is called nitrogen fixation.

Question 35

Explain denitrifying bacteria

Answer 35

Found mostly in waterlogged soils. They convert nitrates into nitrogen gas.

Question 36

How does a root hair cell do active uptake ?

Answer 36

It requires oxygen for aerobic respiration to provide the energy needed for this active uptake

Question 37

What is calcium needed for in a plant ?

Answer 37

for cell walls

Question 38

What is magnesium needed for in plants ?

Answer 38

for chlorophyll

Question 39

How are root hair cells adapted for their function?

Answer 39

They have an extended shape which increases the SA so they can increase the uptake of nitrates

Question 40

What does eutrophication mean ?

Answer 40

The process occurring in areas of fresh water which have too many nitrates, leading to the death of animal species

Question 41

How can the plants on the water bed be affected by eutrophication ?

Answer 41

Not enough sunlight will reach them and they will die because they cannot photosynthesise

Question 42

How can the fish be affected by eutrophication ?

Answer 42

The plants on the surface will use up all the oxygen in the water and will leave not enough for the fish

Question 43

What are the features of a sustainable woodland ?

Answer 43

- only a small number of large trees are harvested at a time - sapling are planted to replace every tree cut down (reforestation) - harvesting only takes place in one area every 25-30 years (allows trees to grow again)

Question 44

Name one international protocol to help with climate change.

Answer 44

Kyoto protocol 1997. 195 countries agreed to try and help the fight against climate change