Genetics ( Test 3)

Question 1

What is sexual reproduction

Answer 1

The process involving the fusion of the nuclei of two gametes to form a zygote (fertilised egg cell) and the production of offspring that are genetically different from each other

Question 2

Names of sex cells in plants and animals

Answer 2

Animal- Sperm and Ovum
Plant- Pollen nucleus and Ovum

Question 3

How many chromosomes does a gamete have and what do we call them

Answer 3

23 chromosomes ( haploid)

Question 4

What is asexual reproduction

Answer 4

The process resulting in genetically identical offspring (clones) being produced from one parent

Question 5

What is binary fission

Answer 5

When bacteria produces exact genetic copies of them self by asexual reproduction which creates 2 identical daughter cells.

Question 6

What type of cell division is needed for asexual reproduction

Answer 6

Mitosis

Question 7

What type of cell division is needed for sexual reproduction

Answer 7

Meiosis

Question 8

What is a genome

Answer 8

The entire set of the genetic material of an organism

Question 9

What is a gene

Answer 9

A section of DNA that codes for a particular sequence of amino acids which form proteins

Question 10

What is DNA

Answer 10

The genetic material found in the nucleus of the cell

Question 11

What is DNA made up of

Answer 11

DNA is a polymer made up of two strands coiled around to make a double helix

Question 12

What is a nucleotide

Answer 12

A nucleotide is made of a sugar and a phosphate group, with one of four different bases, A, C, T or G, attached. The nucleotides join together, forming two strands. These form a double helix structure. The double helix is held together by weak hydrogen bonding between complementary base pairs.

Question 13

Describe the role of nucleotides in the structure of DNA

Answer 13

The phosphate and sugar section of the nucleotides form the ‘backbone’ of the DNA strand (like the sides of a ladder) and the base pairs of each strand connect to form the rungs of the ladder

Question 14

Name the 2 stages that occur in protein synthesis

Answer 14

Transcription and translation

Question 15

What is transcription

Answer 15

It takes place in the nucleus and the strand of mRNA that is formed moves out of the nucleus and into the cytoplasm.

Question 16

What is translation

Answer 16

It takes place in the cytoplasm when the mRNA strand attaches to the ribosome

Question 17

Name the complementary base pairs in mRNA

Answer 17

Cytosine and Guanine
Adenine and Thymine

Question 18

Name the complementary base pairs in tRNA

Answer 18

Cytosine and Guanine
Adenine and Uracil

Question 19

Describe what occurs in translation

Answer 19

This stage of protein synthesis occurs in the cytoplasm. The ribsome reads the code on the mRNA in groups of 3, each triplet of bases/ codon codes for an amino acid

Question 20

Why must DNA first be transcribed into mRNA before it can be translated into a protein

Answer 20

DNA cannot travel out of the nucleus to the ribosomes (it is far too big to pass through a nuclear pore) so the base code of each gene is transcribed into an RNA molecule called messenger RNA (mRNA).

Question 21

What is an allele

Answer 21

A variation of a gene which can be dominant or recessive

Question 22

Homozygous meaning

Answer 22

If the two alleles of a gene are the same we describe the individual as homozygous

Question 23

Heterozygous meaning

Answer 23

If the two alleles of a gene are different we describe the individual as heterozyous

Question 24

Genotype meaning

Answer 24

The combination of alleles that control each characteristic

Question 25

Phenotype meaning

Answer 25

The observable characteristics of an organism

Question 26

Dominant allele meaning

Answer 26

A dominant allele is always expressed even if only one copy is present

Question 27

What is monohybrid inheritance

Answer 27

Inheritance of characteristics controlled by a single gene

Question 28

Is the male or female responsable for determining the sex of the child?

Answer 28

Male because female chromosomes are XX whereas male chromosomes are XY

Question 29

What are the four main blood groups?

Answer 29

A, AB, B, O

Question 30

Is blood type O the recessive or dominant allele?

Answer 30

Recessive

Question 31

Explain what polygenic means and give an example

Answer 31

Characteristics that are controlled by more than one gene an example of this is eye colour

Question 32

Define variation

Answer 32

Differences between individuals of the same species

Question 33

What is continuous variation?

Answer 33

Continuous variation is when there are very many small degrees of difference for a particular characteristic between individuals and they are arranged in order and can usually be measured on a scale. Examples include height, mass, finger length

Question 34

What is continuous variation?

Answer 34

Continuous variation is when there are very many small degrees of difference for a particular characteristic between individuals and they are arranged in order and can usually be measured on a scale. Examples include height, mass, finger length

Question 35

What is discontinuous variation

Answer 35

Discontinuous variation is when there are distinct differences for a characteristics. For example, people are either blood group A, B, AB or O

Question 36

How is continuous variation found on a graph

Answer 36

It has a bell shaped curve

Question 37

Is discontinuous variation usually caused by genetic variation or environmental variation or both?

Answer 37

Genetic variation

Question 38

Is continuous variation usually caused by genetic variation or environmental variation or both?

Answer 38

Both, genetic and environmental variation

Question 39

Define a zygote

Answer 39

Fertilisation is the fusion of the nucleus of a male gamete with the nucleus of a female gamete, producing a new cell called a zygote

Question 40

Define phenotypic variation and what can it be caused by

Answer 40

Phenotypic variation is the difference in features between individuals of the same species. It can be caused by genetic and environmental variation.

Question 41

Compare mitosis and meiosis

Answer 41

Meiosis produces four genetically different daughter cells while mitosis produces two genetically identical daughter cells. Meiosis produces haploid cells, mitosis produces diploid cells

Question 42

What is found in the nucleus of eukaryotic cells?

Answer 42

Chromosomes which are long coiled up molecules of DNA

Question 43

What takes place in sexual reproduction?

Answer 43

At fertilisation the male gamete fuses with the female gamete to form a fertilised egg known as a zygote which is diploid. The zygote then undergoes cell division by mitosis and develops into an embryo ( which inherits characteristics from both parents as it has a mixture of chromosomes).

Question 44

Descrbe what happens in meiosis

Answer 44

Before the cell divides it duplicates DNA so there is enough for the new cell. In the first division the chromosomes line up in pairs in the centre in a pair there is both a mother and father chromosome. The pairs are pulled apart. In the second division the chromosomes line up at the centre and the chromatids are pulled apart. You get four genetically different haploid daughter cells which are gametes as they have a single set of chromosomes.

Question 45

Define mutations

Answer 45

Mutations are rare, random changes that occur in the sequence of DNA bases in a gene or a chromosome