genetics level 1

Question 1

different forms of the same gene. they can be dominant or recessive

Answer 1

allele

Question 2

reproduction involving only one parent (usually a female). the offspring are genetically identical to the parent and to each other

Answer 2

asexual reproduction

Question 3

parts of dna that are involved in pairing. the bases on dna are cytosine. guanine, adenine and thymine.

Answer 3

base

Question 4

a threadlike structure of nucleic acids and protein found in the nucleus of most living cells. they carry genetic information in the form of genes.

Answer 4

chromosome

Question 5

a self-replicating molecule present in nearly all living organisms. it’s the main constituent of chromosomes

Answer 5

deoxyribonucleic acid

Question 6

an allele which is always expressed, even if only one is present. usually given an upper case letter

Answer 6

dominant

Question 7

male or female reproductive cells (sperm and ova) that contain half the number of chromosomes compared to the parent cell

Answer 7

gamete

Question 8

a short length of DNA that carries the genetic code for a particular characteristic or cell activity

Answer 8

gene

Question 9

the pairs of alleles an organism has for particular traits

Answer 9

genotype

Question 10

an individual with two alleles that are different for a particular trait

Answer 10

heterozygous

Question 11

having the same structural features and pattern of genes

Answer 11

homologous

Question 12

an individual with two alleles that are the same for a particular trait

Answer 12

homozygous

Question 13

a type of cell division that results in four daughter cells, each with half the number of chromosomes of the parent cell (e.g. the production of gametes and plant spores)

Answer 13

meiosis

Question 14

a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus (e.g. tissue growth and repair

Answer 14

mitosis

Question 15

a change in the base sequence of dna

Answer 15

mutation

Question 16

nucleotides form the basic structural unit of dna. composed of a sugar, a phosphate and a base

Answer 16

nucleotide

Question 17

a diagram that shows the phenotypes of related individuals

Answer 17

pedigree chart

Question 18

the observable characteristics of an individual resulting from its genotype

Answer 18

phenotype

Question 19

a group of identical individuals that always produce offspring of the same phenotype when interbred

Answer 19

pure bleeding

Question 20

an allele which is only expressed when two of them are present. usually given a lower case letter

Answer 20

recessive

Question 21

reproduction involving only two parents. the offspring are different to the parent and to each other.

Answer 21

sexual reproduction

Question 22

the organism in question is crossed with an organism that is homozygous for the recessive trait, and the offspring of the test cross are examined

Answer 22

test cross

Question 23

a genetically determined characteristic

Answer 23

trait

Question 24

the differences between organisms within a population. can be continuous or discontinuous

Answer 24

variation

Question 25

a fertilised ova (egg) that contains the full set of chromosomes

Answer 25

zygote