The role of a species in its ecosystem: its habitat, its interactions with other species and the abiotic conditions it tolerates.

How is a niche different from a habitat?

A habitat is only where an organism lives. The niche is its whole role in the ecosystem.

What is an adaptation?

An inherited feature that increases an organism's chance of survival and reproduction in its environment.

Name the three types of adaptation.

Anatomical (structural), physiological (processes in the body) and behavioural (the way an organism acts).

Give an anatomical adaptation of marram grass.

Rolled leaves with stomata in hair-lined pits, which trap humid air and reduce water loss.

Give a behavioural adaptation of emperor penguins.

Huddling together, which reduces the surface area exposed to the cold and so heat loss.

Give a physiological adaptation of Antarctic fish.

Antifreeze proteins in the blood, which stop ice crystals forming.

What causes variation in a population?

Different alleles, which arise by mutation, and the mixing of alleles in sexual reproduction.

What is a selection pressure?

An environmental factor, such as predation, disease or competition, that affects survival and reproduction.

List the steps of natural selection.

Variation, struggle for survival, survival and reproduction of the best adapted, alleles passed on, allele frequency changes.

A change in the allele frequencies of a population over generations.

Why is it wrong to say that individual bacteria become resistant because they need to?

Resistance alleles arise by random mutation; antibiotics select the resistant bacteria that already exist.

What does natural selection act on, and what changes as a result?

It acts on the phenotypes of individuals, and the allele frequencies of the population change.

Niche, adaptation and natural selectionEdexcel A-Level Biology A: Flashcards

Card 1 of 130 of 13 known

Question

What is a niche?

Tap or press Space to reveal

Tap card or press Space to flip

See all 13 cards

What is a niche?: The role of a species in its ecosystem: its habitat, its interactions with other species and the abiotic conditions it tolerates.
How is a niche different from a habitat?: A habitat is only where an organism lives. The niche is its whole role in the ecosystem.
What is an adaptation?: An inherited feature that increases an organism's chance of survival and reproduction in its environment.
Name the three types of adaptation.: Anatomical (structural), physiological (processes in the body) and behavioural (the way an organism acts).
Give an anatomical adaptation of marram grass.: Rolled leaves with stomata in hair-lined pits, which trap humid air and reduce water loss.
Give a behavioural adaptation of emperor penguins.: Huddling together, which reduces the surface area exposed to the cold and so heat loss.
Give a physiological adaptation of Antarctic fish.: Antifreeze proteins in the blood, which stop ice crystals forming.
What causes variation in a population?: Different alleles, which arise by mutation, and the mixing of alleles in sexual reproduction.
What is a selection pressure?: An environmental factor, such as predation, disease or competition, that affects survival and reproduction.
List the steps of natural selection.: Variation, struggle for survival, survival and reproduction of the best adapted, alleles passed on, allele frequency changes.
What is evolution?: A change in the allele frequencies of a population over generations.
Why is it wrong to say that individual bacteria become resistant because they need to?: Resistance alleles arise by random mutation; antibiotics select the resistant bacteria that already exist.
What does natural selection act on, and what changes as a result?: It acts on the phenotypes of individuals, and the allele frequencies of the population change.

Exam questions on Niche, adaptation and natural selection

Marram grass grows on exposed sand dunes, where water drains away quickly and strong winds dry the air. Its leaves are rolled lengthways, with the stomata on the inner surface in pits lined with hairs. It also has long roots that reach deep into the sand.
Explain how the rolled leaves and stomata in hair-lined pits help marram grass to survive on the dunes.2 marks
Male emperor penguins incubate their eggs through the Antarctic winter. The males huddle tightly together and take turns to stand at the cold outer edge of the huddle. Each penguin has densely packed, overlapping feathers and a thick layer of fat under the skin. During incubation the males fast and lower their metabolic rate.
Explain how huddling increases the chance of a male penguin surviving the winter and breeding successfully.2 marks
In the 1950s warfarin, a poison that causes fatal internal bleeding, was used to kill brown rats on farms in Britain. Within a few years warfarin-resistant rats were found in some areas. Resistance is caused by an allele of one gene that arose by mutation and is inherited. Before warfarin was used, the allele was very rare in the rat population.
Explain how the frequency of the resistance allele in the rat population increased.3 marks

See the full worksheet

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).