B1 Organisms in the environment T1

Question 1

Define community

Answer 1

organisms of different species that live in a particular area

Question 2

Define ecosystem

Answer 2

all interacting biotic and abiotic factors

Question 3

Define habitat

Answer 3

place where an organism lives

Question 4

Define population

Answer 4

number of organisms of one species in a habitat

Question 5

(5 points)

Explain why biodiversity is important?

Answer 5

• provides new material e.g. medicine
• regulates climate
• food chains
• more habitats
• nutrient cycling

Question 6

(5 points)

Give reasons for global biodiversity decreasing?

Answer 6

• alien species
• islandisation
• deforestation/habitat loss
• climate change/ pollution
• overharvesting/fishing

Question 7

Define distribution

Answer 7

placement of organisms

Question 8

Define abundance

Answer 8

number of organisms

Question 9

What are transects used for?

Answer 9

DISTRIBUTION

Question 10

[5 marks]

Describe how you would investigate distribution using the quadrat method?

Is this random sampling or transect method?

Answer 10

1. stretch a tape measre through area you want to measure
2. put quadat at beginning of tape (0)
3. Record number of different species/number of 1 species growing in a quadrat
4. Repeat by movung your quadrat along at regular intervals e.g. 2 metres
5. Repeat at different areas (parallel transects)

TRANSECT

Question 11

Why random sampling method is used?

Quadrat method

Answer 11

• measure abundance
• find % cover (an estimate of the area within the quadrat that a plant species covers)

Question 12

What is random sampling used to measure?

Answer 12

ABUNDANCE

Question 13

(4 points)

Describe how you would use the random sampling method to investigate the population size?

Answer 13

1. lay a quadrat randomly (using a grid and rolling dice for the coordiantes -> reduces bias)
2. count organisms completeley within frame (improves accuracy of results)
3. repeat multiple times with several quadrats -> reliable results (find mean per quadrat)
4. work out population size ( population size = total area/quadrat size x mean number of organisms) to calculate abundance

Question 14

Control variables of random sampling method

Answer 14

• same size quadrats
• same species of plants
• same time time of year
• same method of counting plants in quadrat (partially on 2 sides OR only plants fully in)

Question 15

(4 points)

Explain how abiotic factors affect organisms

Living or non-living?

Answer 15

1. light intesity - INCREASE - increases plant population - more photosynthesis
2. temperature - INCREASE (moderate temp) - DECREASE (too hot/cold -> can’t survive unless adapted)
3. availability of water - INCREASE - animal and plant population survive
4. availability of oxygen and carbon dioxie - INCREASE 1.animal - oxygen needed for respration 2. plant - carbon dioxide to photosynthesise

Non-living

Question 16

(4 points)

Explain how biotic factors affect organisms

Living or non-living?

Answer 16

1.light intesity - INCREASE - increases plant population - more photosynthesis

Living

Question 17

Define biodiversity

Answer 17

Variety of plant and animal life