story of us - part 1

Question 1

name the bases

Answer 1

• adenine
• thymine
• cytosine
• guanine

Question 2

what is a gene

Answer 2

a short section of DNA that codes for a particular protein

Question 3

what is a genome

Answer 3

the entire DNA of an organism

Question 4

where is genetic information found

Answer 4

nucleus

Question 5

describe the structure of DNA

Answer 5

• 2 strands (double stranded)
• complimentary base pairing
• made of nucleotides (polynucleotide)
• double helix
• sugar-phosphate backbone

Question 6

how many chromosomes are there in all human body cells (except gametes), and how are they arranged

Answer 6

46, arranged in 23 pairs

Question 7

how many chromosomes are there in human gametes

Answer 7

23

Question 8

in humans, of the 23 pairs, what are 22 of the pairs called

Answer 8

autosomes

Question 9

what are the 23rd pair of chromosomes called

Answer 9

sex chromosomes

Question 10

what are pairs of matching chromosomes called

Answer 10

homologous pairs

Question 11

what is an allele

Answer 11

an alternate form of a gene

Question 12

what is a chromosome

Answer 12

made of DNA, genes located on, found in the nucleus

Question 13

diploid definition

Answer 13

number of chromosomes found in body cells

Question 14

haploid definition

Answer 14

number of chromosomes found in gametes

Question 15

dominant definition

Answer 15

different forms of the same gene

Question 16

recessive definition

Answer 16

allele that is not expressed in phenotype when dominant allele is present

Question 17

codominance definition

Answer 17

both alleles are expressed in the phenotype

Question 18

what does adenine always pair with

Answer 18

thymine

Question 19

what does cytosine always pair with

Answer 19

guanine

Question 20

variation definition

Answer 20

differences between individuals of the same species

Question 21

what are the 3 causes of variation in humans

Answer 21

environmental, genetic, a combination of both

Question 22

phenotypic variation definition

Answer 22

variability in the phenotype that exists in a population because of genetic variation and environmental factors

Question 23

discontinuous variation:

Answer 23

• usually caused by genetic variation alone
• where there are distinct differences for characteristics
• for example, blood group or eye colour
• display data using bar chart

Question 24

continuous variation:

Answer 24

• often vary because of a combination of genetic and environmental causes
• when there are very small degrees of difference for a characteristic
• for example, height, mass, intelligence
• display data using a histogram with a normal distribution curve - usually gives a smooth bell curve because of the small degrees of differences

Question 25

what are phenotypic features

Answer 25

observable + measurable characteristics of an individual that can be affectedly environmental factors + genetics

Question 26

homozygous definition and example

Answer 26

same alleles

e.g. bb

Question 27

heterozygous definition and example

Answer 27

different alleles

e.g. Bb

Question 28

polygenic inheritance definition

Answer 28

many characteristics controlled by two or more genes working together

Question 29

what does a pedigree diagram show

Answer 29

the family history of a genetic condition