B6: Inherirance, Variation And Evolution (triple)

Question 1

What are chromosomes?

Answer 1

Long molecules of DNA

Question 2

What is a gene?

Answer 2

A small section of DNA found on a chromosome

Question 3

What do genes do?

Answer 3

They are the code for a particular sequence of amino acids which are put together to make a specific protein.

Question 4

What is a Genome?

Answer 4

The entire set of genetic material in an organism.

Question 5

What is sexual reproduction?

Answer 5

Involves the fusion of male and female gametes. Because there are two parents, the offspring contain a mixture of their parents’ genes.

Question 6

What is asexual reproduction?

Answer 6

There is only one parent cell so the offspring are genetically identical.

Question 7

Describe meiosis.

Answer 7

1. Original cell duplicates, it forms 2 armed chromosomes (each side a copy of the other)
2. In the first cell division, the chromosome pairs line up in the centre of the cell.
3. The pairs are then pulled apart so each new cell only has one copy of each chromosome
4. In the second division, the chromosomes line up again in the centre of the cell. The arms of the chromosomes are pulled apart.
5. The cells split and you get 4 gametes, each with only a single set of chromosomes in it. Each are genetically different.

Question 8

What are the 23rd set of chromosomes to humans and what do they do?

Answer 8

They are XY or XX and they decide the gender. XX is female and XY is male.

Question 9

What are alleles?

Answer 9

Different versions of the same gene.

Question 10

What is the difference between homozygous and heterozygous genes?

Answer 10

Heterozygous has two different alleles

Homozygous has two of the same alleles

Question 11

What is meant by phenotype?

Answer 11

The characteristic given by alleles.

Question 12

What is speciation?

Answer 12

When the phenotype of and organism has changed so much that a completely new species has formed. They become reproductively isolated.

Question 13

What are 5 ways in which a species can become extinct?

Answer 13

Environmental change
New predator
New disease
Can’t compete with other species
Catastrophic event

Question 14

What is selective breading?

Answer 14

When organisms with desirable characteristics are bread to to produce desirable offspring.

Question 15

What is the main drawback of selective breeding?

Answer 15

The gene pool is reduced as only certain traits are carried forward.

Question 16

What are the three ways in which fossils can form?

Answer 16

From gradual replacement by minerals

From casts or impressions

From preservation in places where no decay happens

Question 17

Describe how antibiotic resistant bacteria can occur.

Answer 17

There is a variation in the population
Bacteria with traits that allow them to survive antibiotics live
Bacteria with no favourable traits die off
Resistant bacteria reproduce and antibiotic becomes ineffective

Question 18

What are the 3 domains of the three-domain system?

Answer 18

Archaea (primitive bacteria)
Bacteria
Eukaryota

Question 19

In the Linnaean system how are kingdoms subdivided?

Answer 19

Kingdom 
Phylum
Class
Order
Family
Genus 
Species

Question 20

What is the binomial system?

Answer 20

1st part refers to genus
2nd part refers to species

Used worldwide as a standard system for naming organisms

Question 21

In DNA, what are the polymers made up of?

Answer 21

Repeating units called Nucleotides.

Question 22

What makes up one Nucleotide?

Answer 22

1 sugar molecule
1 phosphate molecule
1 ‘base’

Question 23

What are the 4 different bases in DNA?

Answer 23

A, T, C and G

Question 24

Describe complementary base pairing.

Answer 24

An A base will always pair with a T.

A C base will always pair up with a G.

Question 25

In DNA, a sequence of how many bases codes each amino acid?

Answer 25

3

Question 26

What decides the order of amino acids in a protein?

Answer 26

The order of bases in a gene.

Question 27

What do the parts of DNA do that aren’t used for coding proteins?

Answer 27

They switch genes on and off genes, so control whether the gene is expressed or not.

Question 28

What does the molecule mRNA do?

Answer 28

It carries the code between the nucleus and the ribosomes so the ribosomes can make proteins.

Question 29

How are the correct amino acids brought to the ribosomes to make proteins?

Answer 29

using carrier molecules.

Question 30

What do mutations do to DNA?

Answer 30

they change the sequence of the DNA bases in a gene, creating a different form of the gene.

Question 31

What are insertions?

Answer 31

when a new base is inserted into the DNA base sequence.

Question 32

What are deletions?

Answer 32

when a base is deleted form the DNA base sequence.

Question 33

what are Substitutions?

Answer 33

when a random base in the DNA base sequence is changed to a different base.

Question 34

How can plants be cloned by tissue culturing?

Answer 34

a few plant cells are grown in a growth medium with hormones into new cloned plants.

Question 35

How can plants be cloned with cuttings?

Answer 35

cuttings from a plant can be taken and planted to grow new clones of the parent plant.

Question 36

How can animals be cloned using embryo transplants?

Answer 36

the sperm and egg are taken form the parents with desirable genes and the egg is artificially fertilised. before the embryo is split before the cells specialise so they can be implanted into another animal.

Question 37

How can animals be cloned using Adult cell cloning?

Answer 37

an egg cell is taken and the nucleus is removed. An adult body cell also has it’s nucleus removed which is then inserted into the empty egg cell. This new cell is stimulated with an electric shock and the embryo is implanted into the womb of an adult female.