Monohybrid inheritance

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?

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 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.

The human body protects itself from pathogens.

Describe how the skin and the stomach protect the human body from pathogens.

Earwax is produced by specialised cells in the ear.

Earwax can trap and kill bacteria.

People either have wet earwax or dry earwax.

The type of earwax people have is controlled by one gene.

Name the part of a human cell where genes are found.

Name the chemical that genes are made of.

Each person has two alleles for earwax.

Why does a person have two alleles for earwax?

The allele for wet earwax is dominant.

E = allele for wet earwax e = allele for dry earwax

Which word describes a person with the alleles Ee?

Tick (✓) one box.

Heterozygous

Phenotype

Recessive

A person with the genotype Ee and a person with the genotype ee plan to have a child.

Complete Figure 9 to determine the probability that the child will have dry earwax.

You should identify any offspring genotype that would have dry earwax.

Figure 9

Type of earwax is only affected by a gene.

Height is a characteristic that is affected by genes and environmental factors.

Give one other human characteristic that is affected by genes and the environment.

Do not refer to height in your answer.

Give one environmental cause for the variation in the characteristic you named in Question 06.7.

Earwax is produced by specialised skin cells in the ear.

Suggest one advantage of producing earwax.

People produce either wet earwax or dry earwax.

The type of earwax people have is determined by one gene.

Define the term ‘gene’.

Scientists studied the type of earwax produced by a large number of parents and their offspring.

Table 1 shows the type of earwax of the parents and the number of offspring with each type of earwax.

The allele for wet earwax is dominant.

Give the evidence from Table 1 that shows the allele for wet earwax is dominant.

Consider the offspring born when one parent has wet earwax and one parent has dry earwax.

Explain the number of offspring with each type of earwax born to these parents.

Assume the parent with wet earwax is heterozygous.

Use Table 1.

You should: draw a Punnett square diagram identify each offspring phenotype explain the number of each type of offspring shown in Table 1.

Use the symbols: E = allele for wet earwax e = allele for dry earwax

Organisms have been genetically modified (GM) for many reasons.

What has been genetically modified to produce a hormone that reduces blood glucose concentration?

Tick (✓) one box.

Algae

Bacteria

Viruses

Scientists are researching the production of GM pigs.

Organs from GM pigs could be transplanted into humans.

What is one advantage of using organs from GM pigs instead of using organs from human donors?

Describe how a human gene could be used to genetically modify a pig embryo.

Farmers produce cotton from cotton plants.

Figure 7 shows a cotton plant.

Insects feed on cotton plants.

Cotton plants have been genetically modified to produce a pesticide that kills insects.

Give one advantage to a farmer of growing cotton plants that are able to kill insects.

Bollworms are insects that eat cotton plants.

Most bollworms are killed if they eat the GM cotton.

Some bollworms have a gene that allows the bollworm to eat GM cotton and survive.

The allele for being killed by eating GM cotton is dominant.

The allele for being able to eat GM cotton and survive is recessive.

Two bollworms mate. Both bollworms would be killed by eating GM cotton.

80 offspring are produced.

Some offspring are able to eat GM cotton and survive.

Predict how many of the 80 offspring are likely to be able to eat GM cotton and survive.

You should:

draw a Punnett square diagram

identify the genotypes of the two parent bollworms

identify the phenotype of each offspring genotype

use the symbols: B = dominant allele b = recessive allele

Predicted number of offspring that will be able to eat GM cotton and survive = __________________

The allele in bollworms for being able to eat GM cotton and survive is recessive.

A bollworm may evolve that has a new dominant allele that allows the bollworm to eat GM cotton and survive.

Explain how a new dominant allele emerging would cause a greater problem than the recessive allele that already exists.

The tawny owl is one species of bird.

The tawny owl can have grey feathers or brown feathers.

The colour of the feathers is determined by one gene.

The allele for brown feathers is dominant (B).

The allele for grey feathers is recessive (b).

What is the genotype of a tawny owl with grey feathers?

Tick (✓) one box.

BB Bb bb

Two tawny owls mate.

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

Figure 16

What is the probability of the offspring having brown feathers?

Use Figure 16.

Tick (✓) one box.

25% 50% 75% 100%

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.

This question is about genetics.

Figure 3 shows the chromosomes of a man.

What evidence is there that the person is male?

Use Figure 3.

A combination of genes and the environment affect how tall a person is.

Give one other human characteristic that is affected by genes and the environment.

Do not refer to height in your answer.

Cystic fibrosis is an inherited disorder that affects the lungs.

Suggest one symptom caused by damaged lungs.

The allele for having cystic fibrosis is recessive, r.

The allele for not having cystic fibrosis is dominant, R.

What is the genotype of a person with cystic fibrosis?

Tick (✓) one box.

RR Rr rr

A man has the genotype RR.

Which word describes the genotype RR ?

Tick (✓) one box.

Characteristic

Homozygous

Phenotype

A woman has a child with a man.

Complete Figure 4 to show the possible genotypes of the child.

Figure 4

What is the chance of the child having cystic fibrosis?

Tick (✓) one box.

0% 25% 50% 75%

Drugs are being developed to treat cystic fibrosis in humans.

The drugs are tested before being used to treat patients.

Give two reasons why drugs are tested.

The drugs are tested on sheep that have been genetically modified (GM) to develop the symptoms of cystic fibrosis.

Give one ethical argument against the production of sheep with the symptoms of cystic fibrosis.

Do not refer to religion in your answer.

This question is about inheritance.

Complete Figure 8 to show why the probability of a child being a male is 0.5

Figure 8

Cystic fibrosis is an inherited disorder.

The allele for cystic fibrosis is recessive, r.

The dominant allele is R.

A man and a woman plan to have a child.

The man and the woman are both heterozygous for cystic fibrosis.

Determine the probability that the child will be a male with cystic fibrosis.

You should:

draw a Punnett square diagram identify which of the offspring genotypes will have cystic fibrosis.

Some sheep have been genetically modified to develop the symptoms of cystic fibrosis.

Give one ethical argument for the production of sheep with the symptoms of cystic fibrosis.

Do not refer to religion in your answer.

Give one ethical argument against the production of sheep with the symptoms of cystic fibrosis.

Do not refer to religion in your answer.

The sheep were genetically modified as embryos.

Describe the stages involved in producing a genetically modified sheep that shows symptoms of cystic fibrosis.

Figure 5 shows a diagram of blood.

Cells in the blood are specialised to have particular functions.

What process produces specialised cells?

Tick (✓) one box.

Draw one line from each blood component to a function of the component.

Some blood cells carry out phagocytosis.

What is phagocytosis?

Tick (✓) one box.

Cystic fibrosis is an inherited condition.

The allele for not having cystic fibrosis is dominant, R.

The recessive allele is r.

What term describes the genotype Rr ?

Tick (✓) one box.

Having symptoms of cystic fibrosis is a person’s phenotype.

What does the term ‘phenotype’ mean?

Tick (✓) one box.

Two people are planning to have a child.

Complete Figure 6 to show the possible genotypes of the child.

Draw a ring around one of the offspring in Figure 6 that would have cystic fibrosis.

What is the percentage chance of the child having cystic fibrosis?

Tick (✓) one box.

New drugs are being developed to treat the symptoms of cystic fibrosis.

Trials of new drugs are needed to work out the correct dose of the drug to use.

Give one other reason why drugs are trialled before they are used by patients.

Do not refer to dosage in your answer.

Cystic fibrosis is an inherited condition.

The allele for having cystic fibrosis is recessive, r.

The dominant allele is R.

A person who has the genotype Rr is a ‘carrier’ of cystic fibrosis.

Carriers do not have symptoms of cystic fibrosis.

What scientific term describes the carrier’s genotype, Rr ?

Figure 5 shows the inheritance of cystic fibrosis in one family.

Person 6 and person 7 plan to have another child.

Draw a Punnett square diagram to show the probability of the child having cystic fibrosis.

Identify the genotypes of any offspring with cystic fibrosis.

Use Figure 5.

Mucus is produced in the breathing system.

In people with cystic fibrosis the mucus is thicker than the mucus produced in an unaffected person.

Explain why a person with cystic fibrosis has an increased risk of lung infections.

Some medical products are produced by genetically modified (GM) organisms.

Hamsters are small mammals.

GM hamster cells are used to produce drugs to treat some human genetic disorders.

Describe how a human allele can be transferred into the genome of a hamster cell.

Name a medical product that can be produced by GM bacteria.

Give the name of the disorder the product is used to treat.