Genetic variants & mutation

This question is about genetics.

Figure 9 shows two lions.

One lion has brown fur.

One lion has white fur.

White fur colour in lions is caused by a mutation.

How could a mutation cause white fur colour?

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The mutation could cause cells to divide.

The mutation could prevent the growth of cells.

The mutation could stop cells producing a protein.

Lions live in areas of grass.

The dry grass is often brown.

White lions are very rare in the wild.

Explain why natural selection is likely to result in low numbers of white lions in the wild.

The allele for brown fur is dominant.

The allele for white fur is recessive.

A heterozygous male lion and a homozygous recessive female lion produce one offspring.

Determine the probability that the offspring will have white fur.

You should:

complete Figure 10

use the symbols: B = allele for brown fur b = allele for white fur

identify the colour of fur for each offspring genotype

give the probability of the offspring having white fur.

This question is about genetics.

Figure 2 shows two lions.

One lion has brown fur.

One lion has white fur.

White fur colour in lions is caused by a mutation.

How could a mutation cause white fur colour?

Tick (✓) one box.

The mutation could cause cells to divide.

The mutation could prevent the growth of cells.

The mutation could stop cells producing a protein.

Lions live in areas of grass.

The dry grass is often brown.

White lions are very rare in the wild.

Explain why natural selection is likely to result in low numbers of white lions in the wild.

The allele for brown fur is dominant.

The allele for white fur is recessive.

A heterozygous male lion and a homozygous recessive female lion produce one offspring.

Determine the probability that the offspring will have white fur.

You should:

complete Figure 3

use the symbols: B = allele for brown fur b = allele for white fur

identify the colour of fur for each offspring genotype

give the probability of the offspring having white fur.

This question is about plant tissues.

Plant meristem tissue is found in the growing tips of shoots and roots.

Name two processes in plants that only occur in meristem tissue.

An acorn is a nut that contains the seed of an oak tree.

When one type of insect lays an egg in an acorn, the acorn grows abnormally.

The abnormal growth is called a gall.

An insect embryo grows inside the gall.

Figure 8 shows a normal acorn and an acorn that has grown a gall.

The seed in an acorn forms from one original cell with two sets of oak tree chromosomes.

The original cell in each seed was produced by sexual reproduction.

The gall has cells that contain two sets of oak tree chromosomes.

Compare the process that produced the original cell in each seed with the process that produced cells in the gall.

The insect embryo inside the acorn:

causes the growth of the gall

uses nutrients from the gall to grow

causes lignin to form around the outside of the gall.

The lignin around the gall protects the acorn from being eaten by herbivores.

Which other structure in the oak tree contains lignin?

Tick (✓) one box.

Phloem

Root hair cells

Xylem

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.

Ionising radiation is dangerous to humans because it causes mutations which can cause cancer.

Which of the following can be mutated by ionising radiation?

Tick (✓) one box.

Atoms

Genes

Red blood cells

A nucleus of uranium-238 (U) emits an alpha particle (He) and decays into thorium-234 (Th).

Complete the nuclear equation to show the decay of a uranium-238 nucleus by emitting an alpha particle.

Rocks from a uranium mine contain uranium and several other radioactive isotopes.

Table 4 shows information about two isotopes in a sample of rock from a uranium mine.

The initial number of nuclei of each isotope in the sample was the same.

Explain the difference in the number of nuclei of each isotope in the sample after 5.0 days.

Your answer should include calculations.

Scientists collected data about lung cancer in the population of one country.

They used the data to predict the number of cases of lung cancer in people who work in uranium mines.

Table 5 shows the predicted number and the actual number of cases.

What was the percentage increase in the actual number of cases compared with the predicted number of cases?

Tick (✓) one box.

185%

440%

540%

Radon is an odourless, colourless gas that builds up in uranium mines.

Radon nuclei emit alpha radiation.

Explain why the actual number of cases of lung cancer in Table 5 is greater than the predicted number.

The genetic material in a cell is made of DNA.

A DNA molecule is made from two strands twisted around each other.

What scientific term describes the structure of DNA?

Cells divide in a series of stages called the cell cycle.

Figure 13 shows a cell cycle for a human cell.

What happens during the mitosis stage of the cell cycle?

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Chromosomes move to opposite ends of the cell.

Copies of the organelles are made.

The cell increases in size.

Before a cell divides by mitosis, the mass of DNA in the cell is 6 picograms.

What mass of DNA will be in each of the new cells at the end of cell division?

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3 picograms

6 picograms

12 picograms

One cell takes 16 hours to divide and form two new cells.

Estimate the total number of cells produced from one cell at the end of 48 hours.

Use the following steps.

Calculate the number of divisions in 48 hours

Calculate the number of cells after 48 hours

Give one factor that can cause a mutation in DNA.

Do not refer to ionising radiation in your answer.

A mutation in DNA may cause cells to become cancerous.

Figure 14 shows the change in the number of cancerous cells and non-cancerous cells during 6 days.

Describe three patterns shown in Figure 14.

Use data from Figure 14.

Predict the number of non-cancerous cells on day 7 if the pattern from day 4 continued.

You should extend the line for non-cancerous cells on the graph in Figure 14.

Number of cells = ____________________ thousand

Bananas from wild banana plants are not eaten by humans.

Edible banana plants are grown commercially.

Humans can eat bananas from edible banana plants because they do not contain seeds.

The edible banana plant evolved from the wild banana plant.

Figure 12 shows how scientists think the edible banana plant may have evolved.

What is process X in Figure 12 ?

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Explain why the edible banana plant cannot produce gametes.

Cloning is used to reproduce edible banana plants.

The cloned cells divide by mitosis.

Describe the process of mitosis.

Banana plants can become infected by the TR4 fungus.

The fungus enters the plant through the roots and grows within the xylem vessels.

The xylem vessels become blocked and the leaves turn yellow.

Describe why blockage of the xylem vessels causes the leaves to turn yellow.

TR4 fungus is a threat to the global banana industry.

Some wild banana plants have a gene for resistance to the TR4 fungus.

What could scientists do to protect edible banana plants from the TR4 fungus?

Tick (✓) one box.