DNA and the genome

AKU is a genetic disorder.

Figure 3 shows the inheritance of AKU in one family.

Describe how Figure 3 shows that the allele for AKU is recessive.

Which person is definitely heterozygous for AKU?

Tick () one box.

A female who has AKU and a male who is heterozygous for AKU plan to have a child.

Determine the probability that the child will have AKU.

You should:

• complete Figure 4

• identify the phenotype of each offspring genotype

• use the symbols: A = dominant allele a = recessive allele.

A mutation is a change in a gene.

People who have AKU have a mutation that causes the production of a non-functioning enzyme.

Enzymes are proteins.

Suggest how a mutation can result in the production of a non-functioning enzyme.

Some people have In Vitro Fertilisation (IVF) treatment to increase the chance of becoming pregnant.

Describe how the process of IVF can result in pregnancy.

Embryos can be screened to detect inherited disorders.

Give two arguments against embryo screening.

Do not refer to religion in your answer.

This question is about genetics.

Crop plants are genetically modified (GM) for useful characteristics. Which useful characteristic are crops genetically modified for? Tick (✓) one box.

What is one concern about GM crops? Tick (✓) one box.

Some inherited disorders are caused by a faulty piece of DNA.

What is the name of a piece of DNA that codes for a characteristic?

DNA contains a code for making substances in the cell. What type of substance is made using the DNA code? Tick (✓) one box.

Cystic fibrosis (CF) is an inherited disorder. The allele for having CF is recessive (h). The allele for not having CF is dominant (H).

What is a recessive allele? Tick (✓) one box.

A man and a woman do not have CF. The man has the alleles Hh.

What word describes the alleles of the man? Tick (✓) one box.

The man and the woman want to have a child. Complete Figure 1 to show the possible genotypes of the child. Draw a ring around the genotype of a child who will have CF.

What is the chance that a child of the man and the woman will have CF? Tick (✓) one box.

The woman is pregnant. The woman can have embryo screening to find out if the child will have CF. Suggest one reason why the woman might not want to have embryo screening.

This question is about DNA and genes.

Which diagram represents a DNA molecule? Tick (✓) one box.

Describe the structure of a DNA molecule.

A gene is a small section of DNA on a chromosome. Complete the sentences.

A gene codes for a particular sequence of. This sequence makes a specific.

What is meant by the term genome?

The complete human genome is now known. Which important scientific advance was made using knowledge of the human genome? Tick (✓) one box.

A student found six different snails of one species in his garden. Figure 7 shows the snails.

All the snails are different. What scientific term describes differences in characteristics between individuals of a species?

A change in DNA has caused snail P to be very different from the other five snails. Suggest why there might be an increasing number of snails similar to snail P in each future generation.

This question is about DNA and genes.

Which diagram represents a DNA molecule? Tick (✓) one box.

Describe the structure of a DNA molecule.

A gene is a small section of DNA on a chromosome. Complete the sentences.

A gene codes for a particular sequence of. This sequence makes a specific.

What is meant by the term genome?

The complete human genome is now known. Which important scientific advance was made using knowledge of the human genome? Tick (✓) one box.

A student found six different snails of one species in his garden. Figure 1 shows the snails.

All the snails are different. What scientific term describes differences in characteristics between individuals of a species?

A change in DNA has caused snail P to be very different from the other five snails. Suggest why there might be an increasing number of snails similar to snail P in each future generation.

Animals have adaptations to survive in their environment.

These adaptations may be structural, behavioural or functional.

Draw one line from each animal adaptation to the type of adaptation it is.

Animal adaptation
Type of adaptation

Plants also have adaptations.

Orchid plants have adaptations which make them one of the most successful plant groups.

Orchids rely on insects for pollination.

Figure 2 shows an orchid.

Which two features help orchids survive?

Tick (✓) two boxes.

Many orchid species grow in tropical rainforest ecosystems.

What name describes the variety of all the different species found in an ecosystem?

Tick (✓) one box.

Some species of orchid may become extinct because of deforestation.

Give one reason why tropical rainforests are being cut down.

Give one factor that might cause a species of orchid to become extinct.

Do not refer to deforestation in your answer.

Scientists have analysed the entire genetic material of one species of orchid.

What chemical is the genetic material made from?

What is the name for the entire genetic material of an organism?

Animals have adaptations to survive in their environment. These adaptations may be structural, behavioural or functional.

Draw one line from each animal adaptation to the type of adaptation it is.

Animal adaptation Type of adaptation

Plants also have adaptations. There are more than 28 000 known species of orchid plants.

Many orchid plants:

• grow attached to other types of plants

• have brightly coloured flowers

• produce large quantities of pollen

• produce thousands of tiny, light seeds.

Describe how these adaptations help orchid plants to survive and compete.

A rare orchid has been found in the mountains in China. The orchid has pale yellow flowers. DNA analysis of the genome shows that it is an ancestral species. All other present day orchids evolved from this ancestral species millions of years ago.

One present day species has bright purple flowers. Describe how an orchid with bright purple flowers may have evolved from the ancestral species which has pale yellow flowers.

The DNA code determines the sequence of amino acids which are joined together to form a specific protein. Table 3 shows part of the amino acid sequence for the colour pigment protein in five orchid species. The rest of the amino acid sequence is the same for all the species.

ala = alanine gly = glycine isoleu = isoleucine leu = leucine tyr = tyrosine Suggest which orchid species is most closely related to the ancestral species. Give a reason for your answer.

The genetic material in cells is made of DNA.

Which two of the following describe the structure of DNA?

Tick two boxes.

Complete the sentences.

Choose answers from the box.

Gametes (sex cells) contain half the amount of DNA compared to body cells.

Give the names of the two types of gametes in humans.

What is the process called when the gametes join?

Figure 1 shows cell division by meiosis to form gametes.

Which two features in Figure 1 show that this cell division is meiosis and not mitosis?

Tick two boxes.