Variation & Evolution (AQA GCSE Combined Science: Synergy: Life & Environmental Sciences): Exam Questions

Figure 4 shows the evolution of some plants.

A, B, C, D and E show when one species evolved into two species.

Use Figure 4 to answer this question and the following parts.

Give the genus name of salt cress.

Cabbage, cauliflower and kale are all varieties of one species, Brassica oleracea.

How many years ago did rapeseed evolve to become a different species from cabbage, cauliflower and kale?

Give the binomial names of two species that evolved 5 million years ago.

It has taken thousands of years for farmers to produce the different varieties of Brassica oleracea.

Describe how farmers have been able to produce the different varieties of Brassica oleracea.

Describe how scientists can prove that cabbage and cauliflower plants are the same species.

Do not refer to DNA analysis in your answer.

Figure 5 shows the number of genes in Brassica oleracea that are :

• found only in each variety

• found in two of the varieties, and

• found in all three of the varieties.

How does Figure 5 show that cauliflower and kale are more closely related than cauliflower and cabbage?

Scientists discovered a population of mosquitos living in the tunnels of the London Underground train system.

The mosquito 'C. pipiens' entered the tunnels when the London Underground was being built in the 1800s.

Some mosquitos were trapped in the tunnels.

Table 6 gives information about C. pipiens mosquitos.

Table 6

Suggest one reason why the mosquitos living in the tunnels stay active all year round.

Some scientists believe that the mosquitos living in the tunnels have evolved into a new species.

Name the process that causes evolution.

Explain how the mosquitos living in the tunnels could have evolved into a different species from those living above ground.

Most female mosquitos feed on the blood of animals before laying their eggs.

Figure 9 shows the change in the body temperature of a female mosquito while feeding on blood.

Mosquitos control their internal body temperature by homeostasis.

The optimum internal body temperature of mosquitos is 22 °C.

Explain why mosquitos can only feed on blood for a short time.

Patients with HPV infections are at increased risk of cancer.

Suggest what effect HPV has on human DNA.

Two tawny owls mate.

Complete Figure 16 to show the possible genotypes of the offspring.

What is the probability of the offspring having brown feathers?

Use Figure 16.

Scientists investigated the effect of climate change on the number of tawny owls with grey feathers and with brown feathers.

The investigation took place between 1980 and 2020.

Figure 17 shows the results.

The number of tawny owls with brown feathers in the population has increased since 1980.

Give two other conclusions from the data in Figure 17.

Between 1980 and 2020 there was a decrease in the time the area was covered with snow.

The tawny owls with brown feathers are better camouflaged from their prey when there is no snow.

Explain how the increase in the number of tawny owls with brown feathers occurred through the process of natural selection.

In 2018 a scientist claimed to have genetically modified two human embryos.

Why is genetic modification of human embryos illegal in most countries?

Tick (✓) one box.

The scientist claimed the genetic modification was made to embryos immediately after fertilisation.

Why is genetic modification of embryos more of a concern than genetic modification of body tissues in an adult?

Tick (✓) one box.

The scientist claimed that the embryos were genetically modified to be resistant to HIV infection.

Why do some scientists think this use of genetic modification is not necessary?

Tick (✓) one box.

Plant species Q is not resistant to one type of virus.

Explain how the process of natural selection could result in all plants of species Q having resistance to the virus.

Other species of tree are in the same genus as Quercus robur.

What does it mean if two species of tree are in the same genus?

The insects have changed over time and caused a gall to grow on acorns.

The gall increases the chance of survival of the insects inside the gall.

What name is given to the process of the insects changing over time?

A species of grass has the binomial name Lolium perenne.

What is the genus of the grass?

In 2018, a scientist claimed to have genetically modified two human embryos.

Suggest why genetic modification of human embryos is illegal in most countries.

The scientist claimed that the embryos were genetically modified to have a faulty CCR5 gene.

The CCR5 gene codes for a protein that allows HIV to enter cells.

The genetic modification may have caused the embryos to be protected against AIDS.

Suggest how the embryos were genetically modified to make the CCR5 gene faulty.

Many years ago, a mutation of an insect embryo led to the embryo causing lignin production in an acorn.

Explain how the mutation could have produced a population of insects that all cause lignin production.

Humans can use different methods to produce animals and plants with desired characteristics.

Figure 5 shows some different breeds of horse.

All breeds of horse are of the same species.

Suggest what you could do to show this.

Horse racing is an ancient sport.

Selective breeding has been used for centuries to produce racehorses.

Describe the steps involved in selective breeding to produce a racehorse.

Another way of producing organisms with desired characteristics is genetic engineering.

Bt cotton is a variety of cotton that has been genetically engineered to produce a poison.

The poison kills several different species of insect that feed on cotton plants.

The poison is naturally produced by a soil bacterium called Bacillus thuringiensis.

Describe how cotton plants can be genetically engineered to produce the Bt poison.

Describe the advantages and disadvantages of growing Bt cotton.

A person's characteristics can be due to:

• environmental causes

• genetic causes

• both environmental and genetic causes.

Complete Table 5.

Put a tick to show what each characteristic is due to.

Table 5

Draw one line from each key term to the correct definition.

Farmers use selective breeding to control the characteristics in cows.

Table 6 shows the stages of selective breeding in cows.

Complete Table 6 to show the correct order of the stages.

The first stage has been numbered for you.

Table 6

Farmers selectively breed cows for many different reasons.

Suggest two characteristics that cows may be bred for. Do not suggest coat colour.

1. _

2. _

Selective breeding can lead to problems.

Suggest how problems caused by selective breeding in cows can have negative financial effects for the farmer.