Meiosis

A gardener grows a species of plant that has either red or white flowers. The colour of the flowers is controlled by a single pair of alleles, R and r.

The gardener crosses a plant that is homozygous for red flowers with a plant that is homozygous for white flowers. The diagram shows the results.

Explain why the offspring in the diagram are all red.

The offspring are all heterozygous for flower colour.

What is meant by the term heterozygous ?

The gardener grows another species of plant that can produce flowers of five different colours.

The gardener counts the number of plants for each flower colour.

The graph shows their results.

The gardener counted 97 plants.

Calculate the percentage of these plants that have blue flowers.

Give your answer to the nearest whole number.

What evidence is there in the graph that flower colour is an example of discontinuous variation in this species?

The male gametes of a plant are called pollen.

The sentences in the text box are about pollen. There are two words in the sentences that are not correct.

Pollen cells are haploid. This means that the pollen cells of a plant have twice

the number of chromosomes as the leaf cells of the plant.

Pollen cells are formed by a type of cell division called mitosis.

A gardener grows a species of plant that has either red or white flowers. The colour of the flowers is controlled by a single pair of alleles, R and r.

The gardener crosses a plant that is homozygous for red flowers with a plant that is homozygous for white flowers. The diagram shows the results.

Explain why the offspring in the diagram are all red.

The offspring are all heterozygous for flower colour.

What is meant by the term heterozygous ?

The gardener crosses one of these offspring plants with a plant that is homozygous for white flowers.

Predict the probability that the next generation of plants will have white flowers.

Complete the genetic diagram to explain your answer.

The gardener grows another species of plant that can produce flowers of five different colours.

The gardener counts the number of plants for each flower colour.

The graph shows their results.

The gardener counted 97 plants.

Calculate the percentage of these plants that have blue flowers.

Give your answer to the nearest whole number.

What evidence is there in the graph that flower colour is an example of discontinuous variation in this species?

The male gametes of a plant are called pollen.

The sentences in the text box are about pollen. There are two words in the sentences that are not correct.

Pollen cells are haploid. This means that the pollen cells of a plant have twice

the number of chromosomes as the leaf cells of the plant.

Pollen cells are formed by a type of cell division called mitosis.

Which number per cell is halved during meiosis?

A Chromosome

B Gamete

C Haploid

D Nucleus

The diagram shows two cells from a mosquito with a chromosome number of 6.

Different types of cell division produced Cell A and Cell B.

Name the type of cell division that produced Cell A and explain its importance for the mosquito.

Type of cell division........

Sexual reproduction is important for species as it results in differences within a species.

Within a species of mosquito there are some mosquito that need blood to lay eggs and others that do not.

Why is this an example of discontinuous variation?

What is the probability of a baby being male when humans sexually reproduce?

Complete the genetic diagram to explain your answer.

The diagram in Fig. 15.1 shows events that occur during human sperm production.

Cells in the germinal epithelium have the ability to turn into sperm cells.

Which term describes cells that have the ability to turn into specialised cells?

Compare the number of chromosomes in human germinal epithelium cells and human mature sperm cells.

Describe the events that occur at Stage 1 and Stage 2 in Fig. 15.1.

Sperm production occurs best at 35.0 °C due to the enzymes involved.

Explain why the testes are positioned outside of the body cavity.