3.7.4 Ecosystems

Question 1

What’s the difference between interspecific and intraspecific competition?

Answer 1

• interspecific between different species
• intraspecific between the same species

Question 2

Changes in populations (prob graph question)

Answer 2

• n year cycles
• predator peaks after prey
• prey increase due to low numbers of predator
• so more food for predator so numbers increase
• increases predation reduces number of prey
• number predator decreases due to lack of food

Question 3

What are the uses of random sampling?

Answer 3

Good for species with uniform distribution

Question 4

What are the uses of systematic sampling?

Answer 4

Useful to see a graduation from one part of the field to another (factor affecting distribution)

Question 5

How would you investigate the whether the distribution of dandelions changed with increased distance from road?

Answer 5

• lay tape perpendicular to road
• take samples at regular intervals
• using a quadrat
• count numbers or percentage cover of dandelions
• use several transects

Question 6

What does uniform distribution mean?

Answer 6

Same number of organisms in each region

Question 7

What’s the difference between a line transect and a belt transect?

Answer 7

• line:
• laying tape across area habitat
• species that touch the tape are recorded all the way or at intervals
• belt:
• strip taken across an area
• samples taken either continuously along transect or at intervals

Question 8

How do you randomly sample something?

Answer 8

• randomly generate coordinates
• lay 2 tape measures along field at right angles to each other
• place quadrats at these coordinates
• record frequency of species or percentage cover

Question 9

How can we make sampling more representative and reliable?

Answer 9

• reduce bias with random sampling
• reduce the effect of chance with stats tests and large sample size (many)