Reproduction (Inheritance, Variation and Evolution pt1)

Question 1

What does Asexual reproduction involve?

Answer 1

• one parent
• no fusion of gametes ( no mixing of genetic information)
• the production of genetically identical offspring
• mitosis

Question 2

What are examples of asexual reproduction?

Answer 2

• Strawberry plants send out runners which touch the ground and grow a new plant
• daffodils produce lots of smaller bulbs that can grow into new pants
• many fungi reproduce asexually by spores
• Malarial protists reproduce asexually when they are in the human host

Question 3

What does sexual production involve?

Answer 3

• the fusion of male and female gametes: sperm and egg; pollen and egg
• the mixing of genetic information leads to variation in offspring
• formation of gametes involves meiosis

Question 4

How is meiosis carried out?

Answer 4

1) Before the cell starts to divide, it duplicates its genetic information forming to armed chromosomes
2) Chromosomes pairs line up in the centre of the cell
3) Chromosomes part company and move to opposite poles
4) cell divides for the first time
5) Chromosomes line up again in the centre of the cell and the arms of the chromosomes are pulled apart
6) 4 haploid cells are formed, each half the number of chromosomes of the parent cell

all gametes are genetically different from each other

Question 5

How are the 23 pairs of chromosomes restored after meiosis and what happens after this process

Answer 5

in sexual reproduction, 2 gametes, one from male and one from female, join together to restore the full number of chromosomes = fertilisation

new cells divide by mitosis = embryo

cells become specialised by differentiated

Question 6

What are the advantages of sexual reproduction?

Answer 6

• produces variation in offspring
• if the environment changes, variation gives a survival advantage by natural selection
• natural selection can be speeded up by humans in selective breeding to increase food production

Question 7

What are the advantages of asexual reproduction?

Answer 7

• only one pared is needed
• more time and energy-efficient as they don’t need to find a mate
• faster than sexual reproduction
• many identical offspring can be produced when conditions are favourable

Question 8

What are examples of times when organisms using both asexual reproduction and sexual reproduction depending on the circumstance?

Answer 8

• many fungi reproduce asexually by spores but reproduce sexually to give variation
• malaria parasites reproduce asexually in the human host, but sexually in the mosquito
• many plants produce seeds sexually but also reproduce asexually by runners such as strawberry plants, or bulb division such as daffodils

Question 9

What is the genome of an organism?

Answer 9

the entire genetic material of that organism

Question 10

What is a gene?

Answer 10

• a small section of DNA on a chromosome, which codes for a particular sequence of amino acids, to make a specific protein

Question 11

The whole human genome has now been studied.

What does this enable us to do?

Answer 11

• doctors can search for genes linked to different types of disorders
• helps scientists understand the cause of inherited disorders ad how to treat them
• we can use the human genome to trace human migration patterns from the past and how humans may have changed over time

Question 12

Ho many different repeating nucleotides is DNA made from?

Answer 12

4

Question 13

What do the order of bases do?

Answer 13

it controls the order in which amino acids are associated to produce a particular protein

Question 14

What is a mutation?

Answer 14

a random change in DNA structure

Question 15

What is an allele

Answer 15

an alternate form of a particular gene

Question 16

What is a phenotype?

Answer 16

How the alleles are expressed

Question 17

What does homozygous mean?

Answer 17

when two alleles are the same

Question 18

What does heterozygous?

Answer 18

alleles are different

Question 19

What are most characteristics the result of?

what is it called when only one gene is involved?

Answer 19

multiple genes interacting, rather than a single one

monohybrid inheritance

Question 20

What type of allele is Polydactyly (extra fingers or toes)?

Answer 20

dominant

Question 21

What type of allele is Cystic fibrosis?

Answer 21

recessive allele

Question 22

What is embryo screening?

Answer 22

During IVF, before embryo is implanted into the mother’s womb, a cell is removed from each embryo an is analysed for its genes

Embryos do not that have defective alleles are implanted into the women

Question 23

What are the positives of embryo screening?

Answer 23

• screening will stop people from suffering
• treating disorders cost the government a lot of money
• there are laws to stop it from going too far

Question 24

What are the cons of embryo screening?

Answer 24

• screening is expensive
• unethical = many embryos are destroyed
• some people may want to produce an embryo with desirable feature - unethical

Question 25

what are the chromosomes for female and male

Answer 25

female = XX

Male = XY