Inheritance, Variation and Evolution

Explain why lack of FSH in a woman’s blood caused underdeveloped breasts (2)

• lack of FSH causes lack of oestrogen

• breast development is dependent on oestrogen or female secondary sexual characteristics are dependent on oestrogen

Explain why it is important for the number of chromosomes to halve during meiosis (3)

• meiosis forms gametes

• two gametes fuse/fertilise

• to give the normal/correct chromosome number for embyro/offspring

Meiosis produces cells that are genetically different. Describe how meiosis produces cells that are genetically different. (2)

• random chromosome from each pair

• moves to one end of the cell or goes into each new cell/gamete

parents without MSD have a child with MSUD

e.g. 1 and 2 have 5 with MSUD or 7 and 8 have child 12 with MSUD

liver

A person with MSUD cannot make enzyme 2

Explain why the blood of a person with MSUD will have a high concentration of toxic substance P (3)

• no enzyme 2 so cannot break down toxic substance

• toxic substance is still made or builds up over time

• toxic substance diffuses/moves into the blood

Explain why the urine of a person with MSUD will have a high concentration of toxic substance P (2)

• the toxic substance passes through filter in kidney

• nor reabsorbed

Which part of the virus is put into the yeast cell

gene for antigen

Which part of the virus is made by the yeast cell?

(pure) antigen(s)

crop plants grow better

or

crop plants have a higher yield

Suggest one problem of using glyphosate on fields where GM maize is growing

Do not refer to cost in your answer (1)

any one from:

• may kill/harm/poison other plants

• may pollute streams/rivers/soil

• may kill/harm/poison humans or animals

• may alter taste of maize

• may reduce biodiversity

Suggest why scientists cannot be sure what causes a group of animals to become extinct (2)

• no/insufficient evidence

• cannot perform experiment to find out