B13 (Reproduction and Genetics)

Question 1

Gametes

Answer 1

Sex cells and contain 23 chromosomes, one of each from the mother and father

Question 2

Chromosomes

Answer 2

Very long molecules of DNA, found in the nucleus

Question 3

Alleles

Answer 3

different versions of the same gene, that codes for a different version of a characteristic

Question 4

Dominant

Answer 4

When an alleles coded by a phenotype is only in one of the chromosomes

Question 5

Recessive

Answer 5

When an Alleles coded by a phenotype is in both chromosomes

Question 6

Homozygote

Answer 6

Pair of alleles that produces the same characteristics

Question 7

Heterozygote

Answer 7

Pairs of alleles that produce different characteristic

Question 8

Genotype

Answer 8

Description of the pair of alleles present for characteristics

Question 9

Phenotype

Answer 9

Physical expression of the alleles

Question 10

Sexual reproduction

Answer 10

• genetic info transferred 2 different organisms

- eg. Egg and sperm fertilise

Question 11

Asexual reproduction

Answer 11

• only one parent
• this means offspring is a clone of parent
• occurs through mitosis

Question 12

4 Advantages of Sexual (over Asexual)

Answer 12

• variation of offspring
• increased chance of surviving if change environment
• speed up natural selection and pass desirable genes
• increases food production as could destroy genetic diseases

Question 13

3 advantages of Asexual (over sexual)

Answer 13

• only need one parent
• uses less energy as don’t need to find mate
• faster than sexual

Question 14

5 stages of Meiosis (Sexual)

Answer 14

1) Cells divides and duplicates forming 2 chromosomes with genetic info
2) Chromosomes line up in centre
3) Paris pulled apart with parts from each parent
4) 2nd division as chromosomes line up again and pul apart
5) four gametes (daughter cells) each with single set of chromosomes and genetically different

Question 15

3 examples of reproduction both ways

Answer 15

• malaria as reproduce sexually, but asexually in human host
• fungus has asexual spores to produce and asexual spores for variation
• Strawberry produces seeds sexually, then asexually for clones

Question 16

Nucleotides

Answer 16

Strands of polymers that are madd up of repeating units

Question 17

3 Structures of Nucleotides

Answer 17

• one sugar molecule
• one phosphate molecule (backbone)
• one ‘base’ and they make up double helix

Question 18

Bases that join to the sugar

Answer 18

A-T
C-G
- these are complementary base paring

Question 19

Amino acids ordering in structure of DNA

Answer 19

• 3 bases of the gene decide the order of amino acids

- they join to make many proteins depending on the order of the gene

Question 20

Non-coding parts of DNA

Answer 20

• don’t code for proteins and switch genes on and off to make proteins

Question 21

Ribosomes for DNA

Answer 21

• where proteins are made using DNA code

- mRNA copies the DNA and is the messenger between nucleus and ribosomes for the amino acids

Question 22

3 functions of proteins

Answer 22

• enzymes
• hormones
• structure proteins to strengthen tissues

Question 23

Human Genome Project

Answer 23

• complete map of 20,000 genes
• linkage maps track inherited traits/ genetic diseases
• insight so scientists can cure diseases

Question 24

5 stages of completing a punnet square

Answer 24

1) phenotype (Brown Eyes)
2) genotype, parent (BB X bb)
3) Gametes (B,B x b,b)
4) Punnet Square
5) Ratios

Question 25

Cystic Fibrosis

Answer 25

- recessive trait - genetic disorder of cell membrane - build up mucus in air passage and pancreas

Question 26

Polydactyly

Answer 26

- dominant trait | - genetic disorder where you have extra fingers or toes

Question 27

Embryo Screening

Answer 27

- IVF embryos in lab and implanted in womb - take out cells to study genetic disorders - embryos with 'bad' alleles destroyed

Question 28

3 Adv/ 3 Disadv of embryo screening

Answer 28

- stops suffering, treating disorders costs money for government, laws to stop it going too far - implies people with disorders are undesirable, everybody may want to do it, exspensive

Question 29

Male and Female Chromosomes

Answer 29

- Males have X and Y | - Females have X and X

Question 30

Mutations of DNA

Answer 30

- random changes of the DNA - changes the sequence of bases and changes in the proteins - caused by genetic and other factors like radiation

Question 31

3 types of mutations

Answer 31

- insertions where a new base is inserted, with changes the code - deletions are where random bases deleted - substitutions where random bases are changed to a different base