problem 1) A cell in the basal layer of the skin contains 46 chromosomes and divides by mitosis to produce new skin cells. After ten successive divisions, how many chromosomes will the basal cell have? 

problem 2) Choose the most appropriate word to complete the sentence.

When chromosomes replicate, they produce ……...

tissues, nuclei, chromatids, somatic cells

problem 3) In which three of the following cells is mitosis unlikely to occur?

a sperm cell, an epithelial cell of a villus, a hair cell, a cell in the red bone marrow, a red blood cell, a lymphocyte, a cell in the basal layer of the skin

problem 4) An animal has 36 chromosomes in each of its body cells. How many of these chromosomes came from its male parent?

problem 5) Fill in the missing words.

The ….. A …..  of a cell contains a fixed number of chromosomes. Before mitosis, each chromosome ….. B ….. to produce two ….. C …...

problem 6) Give two exs in each case of organs or tissues in which you would expect

(a) meiosis, (b) mitosis to be taking place.

problem 7) A fruit fly has four pairs of chromosomes in its cells. At meiosis, how many different combinations of maternal and paternal chromosomes are possible in the gametes?

problem 8) From the list below, choose the most suitable words to complete the sentence.

Mutations are changes which occur in a ….. A …..or a ….. B …... If a mutation occurs in a cell which is going to form a ….. C ….., the mutation may affect the whole ….. D ….. which develops. Down's syndrome results from a ….. E ….. mutation In the ….. F….. Sickle cell anaemia results from a ….. G ….. mutation which affects ….. H ….. of the blood system.

cells, gene, gamete, chromosome, nucleus, ovum, organism

problem 9) Exposure to ….. A ….., …..  B ….. or ….. C ….. may increase the rate of mutation Suggest words or phrases for A - C

problem 10) What kinds of mutation in disease-causing bacteria might make them more dangerous?