B13 - Reproduction

Question 1

what does sexual reproduciton involve

Answer 1

involves the joining of male and female gametes
- sperm and egg cells in animals
- pollen and eggs cells in folwering plants

Question 2

what does the formation of gametes involve

Answer 2

a type of cell division called meiosis

Question 3

what is sexual reproduction

Answer 3

there is mixing of genetic information which leads to variety in the offspring

Question 4

what is asexual reproduction

Answer 4

involves only one parents and no fusion of gametes, there is no mixing of genetic information so this leads to genetically identical offspring (clones)

Question 5

what does meiosis produce

Answer 5

gametes that have half the normal chromosone number, and so when fertilisation happens, the cell that is produced (zygote) has the full number of chromosones again

Question 6

where in humans does meiosis occur

Answer 6

in the reproductive organs (ovaries and testies)

Question 7

what happens during meiosis

Answer 7

1. copies of the genetic information are made
2. the cell divides twice to form four gametes, each with a single set of chromosones
3. all gametes are genetically different from each other

Question 8

what happens after fertilisation

Answer 8

the cell thats created divides by mitosis over and over again to produce lots of new cells wich differenciate as the embryos develops

Question 9

how is DNA found

Answer 9

in long structures called chromosones

Question 10

what does DNA make up

Answer 10

all of genetic materials in cells, and thats its found in the nuclues

Question 11

what is the structure of DNA

Answer 11

double helix structure

Question 12

what is a gene

Answer 12

a small section of DNA on a chromosone, and that each gene codes for a particular sequence of amino acids which are put together to make a spersific protein

Question 13

what is a genome

Answer 13

the entire genetic material of that organism

Question 14

why is scientists studying the human genome is important

Answer 14

• scientists can search for genes linked to different types of disease
• scientists can undertand and treat inherited disorders
• scientists can trace migration patterns from the past

Question 15

what is a gamete

Answer 15

reproductive cells

Question 16

what is an allele

Answer 16

different versions of the same genes

Question 17

what is a dominat allele

Answer 17

an allele that is always expressed unless the allele is homozgyous

Question 18

what is homozygous

Answer 18

2 of the same alleles

Question 19

what is heterozygous

Answer 19

2 different alleles

Question 20

what is a genotype

Answer 20

the combination of alleles (forms of the gene) that a person has for a particular trait

Question 21

what is a phenotype

Answer 21

The observable characteristics of an organism (seen just by looking - like eye colour, or found – like blood type

Question 22

what are most characteristics a result of

Answer 22

multiple genes interacting rather than a single gene

Question 23

how are some disorders are inherited

Answer 23

inheritence of certain of alleles

Question 24

what is polydactyly

Answer 24

having extra toes and fingers, caused inhertance of dominant alleles

Question 25

what is cystic fibrosis

Answer 25

a disorder of cell memebranes, inherited disorder by a recessive alleles

Question 26

what are some economic, social and ethical judgements for embryo screening

Answer 26

eco:
- expensive, cant be offered to everyone

soc and eth:
-The probability of the couple having a child with a genetic disorder.
- Termination of the pregnancy.
- Therapeutic treatments possible for the child.
- Financial implications of having the child.
- Effect on existing siblings.
- Ethical issues.

Question 27

how many chromosones pairs are there for a normal human

Answer 27

23 pairs 46 single

Question 28

how many chromosones pairs control charcteristics

Answer 28

22 pairs, one of pairs determines sex