Topic 6- Reproduction

Question 1

What are gametes

Answer 1

Sex cells (sperm cells , egg cells,animals)
.Haploid, half the number of chromosomes

Question 2

What is meiosis

Answer 2

. Form of cell division that reduces the number of chromosomes in the parent cell by half and produces 4 gametes.

Question 3

what is sexual reproduction

Answer 3

.Involved the production of gametes by mieosis

.a gamete fron each parent formes to create a zygote

.Genetic information from each gamete is mixed so the resulting zygote is unique

Question 4

What must occur prior to meosis

Answer 4

copies of genetic information are made during this process(the DNA in each chromosome is replicated)

Question 5

What happens during the first stage of mieosis

Answer 5

. Chromosome number is halved
. The pair of chromosomes are seperated and move to opposite sides of the cell

Question 6

what happens during the second stage of mieosis

Answer 6

Four unique haploid gametes are produced

Question 7

Why is mieosis important for sexual reproduction

Answer 7

. It increases genetic variation
.It ensures that the Zygote formed is diploid

Question 8

Describe fertilisation and its resulting outcome

Answer 8

Gametes join together to restore the normal number of chromosomes and the new cell divides by mitosis
As the embyro develops , cells diffrentiate

Question 9

What is the advantages of sexual reproduction

Answer 9

. Creates genetic variation in the offsrping
.Increasing the probability of a species adapting and surviving environmental changes.

Question 10

Disadvantages of sexual reproduction

Answer 10

.More time and energy required,so fewer offspring produced
.Two parents are required

Question 11

What is a-sexual reproduction

Answer 11

.Produces genetically identical offspring known as daughter cells
.Involved mitosis only

Question 12

Advantages of a-sexual reproduction

Answer 12

.Lots of offspring can be produced in a short period of time
. Requires less energy , and do not need to mate

Question 13

Disadvantages of a-sexual reproduction

Answer 13

No genetic variation , except from spontaneus mutations , reducing the probability of a species being able to adapt to environmental change.

Question 14

Describe the circumstances in which malarial parasites reproduce sexually and a-sexually

Answer 14

.Sexual reproduction in the mosquito
.A-sexual reproduction in the human host

Question 15

Describe the circumstances in which fungi reproduces sexually and asexually

Answer 15

Asexual reproduction by spores
Sexual reproduction to give variation

Question 16

Describe the cirumctances in which plants reproduce sexually and asexually

Answer 16

Sexual reproduction to produce seeds

Asexual reproduction by runners

Question 17

What is DNA

Answer 17

.A double stranded polymer of nucleotides, wound to form a double helix
.The genetic material of the cell found in its nucleus.

Question 18

Define genome

Answer 18

The entire genetic material of an organism

Question 19

Why is understanding the human genome important

Answer 19

. Searching for genes linked to different types of disease.
.Understanding and treating inherited disorders
.Tracing human migration patterns from the past

Question 20

What is a chromosome

Answer 20

. A long coiled molecule of DNA that carries genetic information in the form of genes

Question 21

How many chromosomes do human body cells have

Answer 21

46 chromosomes 23pairs

Question 22

Define gene

Answer 22

a small section of DNA that codes fora specific sequence of amino acids which forms a protien.

Question 23

What are alleles

Answer 23

Different versions of the same gene

Question 24

What is a dominant allele

Answer 24

A version of a gene where only one is needed for it to be expressed.

Question 25

What is a recessive allele

Answer 25

A version of a gene where two copies are needed for it to be expressed.

Question 26

what is meant when an organisnm is Homozygous

Answer 26

When an organism has two copies of the same allele (two recessive or dominant)

Question 27

What is meant when an organism is heterozygous

Answer 27

When an organism has two different versions of the same gene (one dominant one recessive)

Question 28

What is the genotype

Answer 28

The genes present for a trait

Question 29

How are dominant alleles represented in a punnet square

Answer 29

They are represented using uppercase letters

Question 30

How are recessive alleles represented in a punnet square

Answer 30

They use the lowercase version of the same letter as the dominant allele

Question 31

Give two examples of inherited disorders

Answer 31

Polydactly- Having extra fingers or toes- Caused by a dominant allele Cystsic fibrosis- A disorder of cell membranes- caused by a recessive allele

Question 32

How are embyros screened for inherited disorders

Answer 32

During IVF , one cell is removed and tested for disorder causing alleles.

Question 33

What are the ethical issues concerning embyro screening

Answer 33

. It could lead to belief in society that having an disorder or disablity , makes on les inferior. .Many see this as murder, as these unborn babies are humans .parents put their unreliable reasons first , other than babies wellbeing.

Question 34

What are the social issues concercning embryo screening

Answer 34

. Social care for children with inherited disorders may need to be considered if parents are unable to provide care .If an embyro , is found to have an inherited disorder and is terminated , this can prevent a childs from suffering in future.

Question 35

what are sex chromosomes

Answer 35

.Males have an X and Y chromosome Females have two X chromosomes