topic 14 - inheritance

Question 1

what is a genome

Answer 1

The entirety of an organism’s DNA

Question 2

what is a gene

Answer 2

a section of DNA which codes for the formation of proteins controlling a specific trait of an organism

Question 3

what are chromosomes

Answer 3

a thread of DNA, made up of genes

Question 4

how many chromosomes do humans have

Answer 4

23 pairs, so 46 chromosomes

Question 5

what is DNA

Answer 5

genetic material found in the nucleus of a cell. it is a polymer made up of two strands coiled around to make a double helix

Question 6

what are alleles

Answer 6

an alternative form of a gene

Question 7

what is a dominant allele

Answer 7

a gene that always shows up in phenotype, even in a heterozygous state

Question 8

what is a phenotype

Answer 8

The visible characteristics of an organism

Question 9

what is a genotype

Answer 9

the genetic makeup of an organism

Question 10

what is a recessive allele

Answer 10

A recessive allele needs to be inherited from both parents for the characteristic to show up in the phenotype.

Question 11

what does homozygous mean

Answer 11

having a pair of same alleles e.g. AA or aa

Question 12

what does heterozygous mean

Answer 12

having a pair of dissimilar alleles e.g. Aa

Question 13

what is a gamete

Answer 13

sex cells

Question 14

what is polygenic inheritance

Answer 14

Characteristics that are controlled by more than one gene. they have phenotypes that can show a wide range of combinations of features

Question 15

what is monohybrid inheritance

Answer 15

the inheritance of characteristics controlled by a single gene

Question 16

how to construct a Punnett Square

Answer 16

1. Determine the parental genotypes
2. Split the alleles for each parent and add them to the Punnett square around the outside
3. Fill in the middle four squares of the Punnett square to work out the possible genetic combinations in the offspring

Question 17

what are family pedigrees

Answer 17

diagrams that are usually used to trace the pattern of inheritance of a specific characteristic (usually a disease) through generations of a family

Question 18

how to interpret family pedigrees

Answer 18

• Males are indicated by the square shape and females are represented by circles
• Affected individuals are red and unaffected are blue
• Horizontal lines between males and females show that they have produced children (which are shown underneath each couple)

Question 19

how is sex determined

Answer 19

• Sex is determined by an entire chromosome pair
• Females have the sex chromosomes XX
• Males have the sex chromosomes XY

Question 20

what is mitosis

Answer 20

nuclear division giving rise to genetically identical cells

Question 21

4 things mitosis is used for

Answer 21

• growth
• repair of damaged tissues
• replacement of cells
• asexual reproduction

Question 22

what is a diploid nucleus

Answer 22

a nucleus containing 23 pairs of chromosomes e.g. general body cells

Question 23

what is a haploid nucleus

Answer 23

a nucleus containing 23 unpaired chromosomes e.g. sex cells

Question 24

process of mitosis

Answer 24

1. The parent cell duplicates itself
2. the replica splits into 2 daughter cells that are genetically identical, with no genetic variation

Question 25

what is meiosis

Answer 25

nuclear division that gives rise to cells that are genetically different

Question 26

process of meiosis

Answer 26

1. parent cell duplicates itself
2. the replica splits into 2 daughter cells
3. the 2 daughter cells produce 4 daughter cells which are genetically different, leading to genetic variation

Question 27

differences between mitosis and meiosis

Answer 27

1. mitosis produces 2 daughter cells, meiosis produces 4 daughter cells
2. mitosis produces diploid daughter cells, meiosis produces haploid daughter cells
3. in mitosis, 1 cell division occurs, in meiosis, 2 cell divisions occur

Question 28

what is the idea of random fertilisation

Answer 28

During fertilisation, any male gamete can fuse with any female gamete to form a zygote. This random fusion of gametes at fertilisation creates genetic variation between zygotes as each will have a unique combination of alleles

Question 29

what is the diploid number of chromosomes in a person

Answer 29

46

Question 30

what is the haploid number of chromosomes in a person

Answer 30

23

Question 31

what is variation

Answer 31

differences between individuals of the same species

Question 32

what is environmental variation

Answer 32

when characteristics are solely focused on environmental factors e.g. climate, diet.

Question 33

what is genetic variation

Answer 33

when characteristics are solely influenced by genetics e.g. parent genes

Question 34

2 examples of environmental variation

Answer 34

• tattoos
• piercings

Question 35

2 examples of genetic variation

Answer 35

• eye colour
• blood group

Question 36

what are mutation

Answer 36

rare, random changes that occur in the sequence of DNA bases in a gene or a chromosome