Meiosis

Scientists think that chickens were domesticated from red junglefowl thousands of years ago.

Figure 4 shows some information about these birds.

Describe how selective breeding has produced chickens that lay large numbers of eggs.

Chickens have 78 chromosomes in each of their body cells.

These chromosomes are in pairs.

Which term describes a chicken body cell?

State the number of chromosomes found in the gametes produced by chickens.

Complete the table to compare the production of body cells and gametes.

One box has been completed for you.

Some animal cells are stem cells.

Describe the function of stem cells.

Figure 8 shows some characteristics of pea plants.

The allele for purple flowers is dominant to the allele for white flowers.

Which term describes the allele for white flowers?

A scientist crossed a pea plant that produced round seeds (Rr) with a pea plant that produced wrinkled seeds (rr).

Complete the Punnett square.

State the percentage of the offspring that will produce round seeds.

percentage =_........ %

The scientist crossed two purple flowering pea plants.

The offspring were:

• 133 plants with purple flowers

• 46 plants with white flowers

Calculate the ratio of offspring with purple flowers to offspring with white flowers.

Give your answer to the nearest whole number.

ratio_........ : 1

Explain why it was possible for this cross to produce some offspring with white flowers.

The cells in pea plants are diploid.

These cells have 14 chromosomes.

Explain why pea plant gametes have only seven chromosomes.

Describe what happens at fertilisation.

Figure 3 shows a diagram of a mouse sperm cell.

Which row of the table shows the functions of structure A and structure B?

The diploid chromosome number for a mouse is 40.

State the number of chromosomes in a mouse sperm cell.

After a mouse egg cell is fertilised, cell division produces a ball of genetically identical stem cells.

Which is the correct order for the stages of one cell division?

The genetically identical stem cells produce the cells that develop into an embryo.

Describe how stem cells produce the cells of an embryo.

Give one scientific reason why the bone marrow transplant in 1968 was from a sister to her brother.

Give one scientific reason why some people are opposed to the isolation of human embryonic stem cells.

Stem cells, with the properties of embryonic stem cells, can be produced from a patient’s own skin cells.

Discuss the benefits of using these stem cells to treat the patient.

Figure 7 shows a height percentile chart for boys.

The numbers on the right-hand side of the graph show the percentiles of the population for each growth curve.

A 10-year-old boy has a height of 140 cm.

Which is the percentile range for height for this boy?

State how percentile charts are used.

As we grow, we make new cells by mitosis and meiosis.

The cells that are made can become specialised.

Figure 8 shows a diagram of a sperm cell.

Describe two ways that the sperm cell is specialised.

Complete the table to show the results when a cell divides by mitosis or meiosis in humans.

Human body cells, except gametes, have 23 pairs of chromosomes.

The tips of plant roots are where many cells are dividing by mitosis.

Which term describes the area of a root where many cells are dividing by mitosis?

Plant root cells contain an enzyme that joins glucose molecules together to make starch.

Devise a plan to investigate the effect of pH on the activity of this enzyme.

Farmers selectively breed chickens to produce larger chickens.

Figure 4 shows how the size of chickens has changed over time.

Explain how farmers have used selective breeding to produce larger chickens.

Describe one benefit and one risk of selectively breeding chickens.

benefit_........

The body cells of chickens have 78 chromosomes in their nuclei.

State the number of chromosomes found in each sex cell of a chicken.

Name the type of cell division which produces sex cells.

What is the correct definition of a genome?

A new project called the Earth BioGenome Project aims to discover the sequence of bases in the DNA for all plants and animals.

State two benefits of discovering the sequence of bases for all plants and animals.

A karyogram is a picture of the chromosomes found in the nucleus of a single cell.

Figure 4 shows a human karyogram.

State two reasons why this karyogram cannot be from a gamete (sex cell).

State the gender shown by this karyogram.

Complete the Punnett square to show how gender is inherited.

State the probability that a child will be male.

Figure 5 shows two sperm cells.

Name structure Z.

Sperm B has a larger middle section than sperm A.

Explain why sperm B will be more likely to fertilise an egg than sperm A if they were both released at the same time.

James Watson and Francis Crick built a model that showed that DNA has a double helix structure.

Which statement about DNA is correct?

Figure 6 shows the percentage of each base in human DNA.

Describe how this data provides evidence for base pairing in DNA.

A scientist obtained a mass of 0.0062 nanograms of DNA from a diploid human cell.

Calculate the mass of DNA the scientist should obtain from a haploid human cell.

Give your answer in picograms.

(1 nanogram = 1000 picograms)

_........ picograms

A student used the method shown in Figure 7 to compare the mass of DNA extracted from strawberry fruit cells and from kiwi fruit cells.

State why ethanol is used.

State two variables the student needs to control when using this method to compare the mass of DNA from these two fruits.

The student repeated the experiment.

Give one reason why.

Mitosis and meiosis are processes that produce new cells.

Compare the outcomes of mitosis and meiosis.

A scientist obtained a mass of 0.0062 nanograms of DNA from a diploid human cell.

Calculate the mass of DNA the scientist should obtain from a haploid human cell.

Give your answer in picograms.

(1 nanogram = 1000 picograms)

_........ picograms

A student used the method shown in Figure 1 to compare the mass of DNA extracted from strawberry fruit cells and from kiwi fruit cells.

State why ethanol is used.

State two variables the student needs to control when using this method to compare the mass of DNA from these two fruits.

The student repeated the experiment.

Give one reason why.

Mitosis and meiosis are processes that produce new cells.

Compare the outcomes of mitosis and meiosis.