Broad Knowledge

Question 1

Define the terms ‘biotic factor’ and ‘abiotic factor’.

Answer 1

Biotic = living organisms that affect ecosystems e.g. predators and diseases

Abiotic = non-living physical and chemical factors that affect ecosystems e.g. climate and pollutants

Question 2

What is the difference between species richness and species abundance?

Answer 2

Species richness = measures the number of different species within an ecosystem

Species abundance = how common a species is relative to its surroundings

Question 3

What is the formula for relative abundance?

Answer 3

number of specific organism / total number of organisms x 100

Question 4

Why do environmental factors limit the species distribution and species abundance?

Answer 4

Because every organism has a tolerance limit and if environmental conditions exceed this limit, the species will not survive in that environment

Question 5

What are the 3 main ways we can classify species?

Answer 5

1. Morphology (shape/structure of physical features)
2. Methods of reproduction (asexual and sexual)
   3.Molecular characteristics (DNA sequencing)

Question 6

Contrast the differences between k-strategists and r-strategists

Answer 6

K-strategist: Prioritise quality (fewer offspring, larger size, late maturity, low mortality).
R-strategists: prioritise quantity (more offspring, smaller size, early maturity, and high mortality)

Question 7

Define the term ‘clade’

Answer 7

Clade = a group of organisms that consists of a common ancestor and all its lineal descendants

Question 8

What are the three assumptions of cladistics?

Answer 8

1. Organisms share a common ancestor
2. Bifurcation (splits in 2, not 3 or more)
3. Distinguishing groups by gradual changes in physical characteristics over generations

Question 9

Define ‘predation’

Answer 9

The relationship between predator and prey, e.g. Bird and worm.

Question 10

Define competition

Answer 10

When two organisms compete for the scarce resources available e.g. Two birds want the same worm.

Question 11

Contrast ‘mutualism’, ‘commensalism’, and ‘parasitism’.

Answer 11

Mutualism is when both species benefit from and interaction, commensalism is when only one species benefits from and interaction and one is neutral, and parasitism is when one organism suffers from and interaction and the other benefits.

Question 12

Define ‘carrying capacity’

Answer 12

Carrying capacity = the population size that can be supported indefinitely on the available ecosystem’s resources.

Question 13

Identify 4 ways that human activity can negatively impact biodiversity.

Answer 13

• Overexploitation: (e.g. overfishing)
• Habitat destruction (e.g. deforestation)
• Monocultures (e.g. wheat fields)
• Pollution (e.g. oil spills)