OCR Gateway GCSE Biology A genes, inheritance and selection (B5) overview quiz quiz

Meiosis makes two genetically identical diploid body cells, just like mitosis does

Meiosis only ever happens during the growth and the repair of body tissues

Meiosis halves the chromosome number and makes four genetically different gametes

Meiosis produces genetically identical clones that show no variation at all

46, because the gametes are simply ordinary body cells just like all of the other cells

92, because the chromosome number doubles when the gametes are made

23, but only in the gametes that are produced by the male parent

23, because meiosis halves the number so the full number is restored at fertilisation

A with T, and C with G

A with C, and T with G

A with G, and T with C

Each base pairs with itself

Body mass is controlled only by the genes a person inherits

Body mass is affected by the environment as well as by genes

Identical twins must actually have slightly different genes

Body mass is fixed at birth and cannot vary during a lifetime

One single base at a time, with each base coding for one whole protein

Backwards, starting from the very end of the messenger RNA molecule

In groups of three bases (triplets), each coding for one amino acid

In pairs of two bases, with each pair coding for one amino acid

Homozygous means two different alleles; heterozygous means two identical alleles

Both mean the organism shows the dominant characteristic

Both refer to the phenotype only

Homozygous means two identical alleles; heterozygous means two different alleles

$3 : 1$ dominant to recessive

$1 : 2 : 1$ dominant to recessive

$1 : 1$ dominant to recessive

All dominant

By the egg, which carries either an X or a Y chromosome from the mother

By the sperm, which carries an X (giving XX, female) or a Y (giving XY, male)

By the total number of chromosomes that are present in all of the body cells together

By the age of the mother at the time that the baby is conceived

Homozygous dominant (FF)

Homozygous recessive (ff)

Heterozygous (Ff)

Carriers do not exist for recessive disorders

The individual bacteria consciously decide to change themselves in order to survive the antibiotic drug that is attacking them

The antibiotic itself directly creates the resistance inside every single one of the bacteria in the population at once

The resistance is simply passed on directly from the body of the infected patient into the bacteria during the illness

A random mutation makes some resistant; the antibiotic kills the rest, and the survivors reproduce and pass on the resistance

Fossils showing how organisms have changed gradually over millions of years

The existence of identical twins who share exactly the same complete set of genes

The fact that all living cells in every organism happen to contain DNA

The presence of vaccines that protect people against many diseases

It directly transfers genes from one separate species into another species

It reduces genetic variation (inbreeding), increasing the chance of inherited defects and disease

It always produces only genetically identical clones of the chosen parent organism every single time

It cannot change a characteristic of the organisms over many generations