B13 Reproduction

Question 1

What is sexual reproduction

Answer 1

This involves the fusion of male and female gametes and there is mixing of genetic information which leads to variety in the offspring. The formation of gametes involves meiosis

Question 2

What is asexual reproduction

Answer 2

involves only one parent and no fusion of gametes. There is no mixing of genetic information. This leads to genetically identical offspring (clones). Only mitosis is involved

Question 3

What is meiosis

Answer 3

Meiosis halves the number of chromosomes in gametes

Question 4

What are the stages of meiosis

Answer 4

copies of the genetic information are made

• the cell divides twice to form four gametes, each with a single set of chromosomes

Question 5

What do all gametes not have in common

Answer 5

They are genetically different from each other

Question 6

What are male gametes

Answer 6

Sperm cells

Question 7

What are female gametes

Answer 7

Egg cells

Question 8

What are the advantages of sexual reproduction

Answer 8

• produces variation in the 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 9

What are the advantages of asexual reproduction

Answer 9

only one parent needed
• more time and energy efficient as do not need to find a mate
• faster than sexual reproduction
• many identical offspring can be produced when conditions are favourable.

Question 10

What are gametes

Answer 10

Sex cells

Question 11

What is a chromosone

Answer 11

These contain the genetic imformation/DNA in the form of a gene and they are in the nucleus

Question 12

What is a gene

Answer 12

A section of DNA that codes for a particular trait or characteristic

Question 13

What is an allele

Answer 13

These are different forms of a gene that code for a different protein so different characteristics are developed

Question 14

What is a dominat allele

Answer 14

This will always be expressed even when there is only one of these alleles present

Question 15

What is a recessive allele

Answer 15

An allele that will only be expressed when both alleles are of this type

Question 16

What is homozygous

Answer 16

An organism with two identical alleles for a ch aracteristic

Question 17

What is heterozygous

Answer 17

An individual with different alleles for a characteristic

Question 18

What is the genotype

Answer 18

This describes the alleles present or genetic makeup of an individual regarding a particular characteristic

Question 19

What is the phenotype

Answer 19

This describes the physical appearance of an individual regarding a particular characteristic

Question 20

What is cystic fibrosis and how is it caused

Answer 20

A disorder of cell membranes that is caused by a recessive allele

Question 21

What is Polydactyly and how is it caused

Answer 21

This is having extra fingers or toes and is caused by a dominat allele

Question 22

In females the sex chromosones are

Answer 22

The same XX

Question 23

In males the sex chromosones are

Answer 23

Different XY

Question 24

How many pairs of chromosones do ordinary human body cells contain

Answer 24

23

Question 25

What is mutation

Answer 25

New forms of genes result from changes in existing genes and these changes are called mutations

Question 26

What is DNA

Answer 26

DNA is a polymer made up of two strands forming a double helix

Question 27

What is the genome of an organism

Answer 27

This is the entire genetic material of that organism

Question 28

Which organsims reproduce by both asexual and sexual reproduction

Answer 28

Malarial parasites, fungi and plants

Question 29

What is mRNA

Answer 29

A single stranded molecule that is made by copying the code from the DNA and carrying to the cytoplasm and ribosomes for protein synthesis

Question 30

What 4 bases does the DNA contain

Answer 30

A C G T

Question 30

What is the code for a particular amino acid

Answer 30

A sequence of three bases

Question 31

What does each nucleotide consist of

Answer 31

A common sugar and a phosphate group with one of the four different bases attached to the sugar

Question 32

What is the structure of DNA

Answer 32

The DNA is a polymer made from 4 different nucleotides and this polymer is made up of repeating nucleotide units

Question 33

In a complementary strand a — is always linked to a — on the opposite strand

Answer 33

C and G | T and A

Question 34

What do parts of the DNA that dont code for proteins do

Answer 34

They switch genes on or off so they control whether or not a gene is expressed (used to make a protein)

Question 35

What are the functions of some proteins

Answer 35

Enzymes as biological catylysts, hormones, structural proteins like collagen