Genetics

Question 1

Sexual reproduction

Answer 1

Joining of two Gametes during fertilisation. Male and female. Organisms have two parents and are genetically similar to both.

ADVANTAGES
Produces variation
Species can adapt to new environments
Disease is less likely all individuals in a population.

DISADVANTAGES
time and energy are needed to find a mate
Not possible for an isolated individual.

Question 2

Asexual reproduction

Answer 2

Only involves 1 parent, no joining of sex cells. Genetically identical to each other and the parent.

ADVANTAGES
Population can increase rapidly when conditions are favourable
Only one parent is needed.
More time and energy efficient
Faster than sexual reproduction

DISADVANTAGES
Does not lead to variation in a population
Species may only be suited to one habitat

Question 3

Meiosis

Answer 3

Produces sex gametes

Produces non-identical haploid cells. Fuse M+F to form a Diploid fertilised egg cell during fertilisation

Question 4

What is DNA Made of?

Answer 4

Deoxyrybonucleic acid is made of Sugars, Phospates and Bases.
These are A,C,T,G. The nucleotides join together forming a double helix. Double helix is held together by weak hydrogen bonds.

Question 5

What is the Human Genome Project?

Answer 5

The HGP was started at the end of the last century. Its aims were to identify all genes, to develop much faster meeans to sequence DNA, and to work out the order or sequence of all 3 billion base pairs in the human genome.

Question 6

Extracting DNA from Fruit Practical

Answer 6

1. Peel skin from kiwi or other fruit and mash it up
2. Mix a teaspoon of salt and washing up liquid into the fruit.
3. Heat the mixture at 60* for 5 mins.
4. Filter the mixture and retain only the filtrate.
5. Cool using an ice bath and pour chilled ethanol on top of the filtrate
6. observe and extract the strands of DNA that appear.

Question 7

Who discovered the structure of DNA?

Answer 7

James watson and Francis crick worked out the structure of DNA in 1953.

Question 8

Name the 4 bases - Full names

Answer 8

Thymine = T
Adenine = A
Guanine = G
Cytosine = C

Question 9

How do the bases pair up?

Answer 9

T always goes with A

C always goes with G

Question 10

How do genes determine which protein to make?

Answer 10

Genes act as a code for making a particular protein. The bases work in triplets, with each triplet coding for a particular amino acid. Amino acids are made in the number and order dictated by the base triplets. Amino acids join together and this determines which protein is produced.

Question 11

Define environmental vs Genetic variation

Answer 11

Every sperm and egg cell contain 1/2 of the information needed to create an individual. When chromosomes fuse during fertilisation a new cell is formed. Examples of Genetic variation include blood type, skin colour and natural eye colour.

Many other kinds of variation may depend on environment a such as a person may inherit a tendency to be tall, but a poor diet throughout childhood could cause poor growth.

Question 12

Define natural selection.

Answer 12

Natural selection describes how organisms that are better at surviving in an environment will survive long enough to reproduce and pass on genes.

Darwins evolution theory was key in this idea. eg: soot covers trees, bright coloured moths would get eaten, dark coloured ones would survive