reproduction

Question 1

what are the two types of reproduction?

Answer 1

Two types of reproduction are sexual and asexual

Question 2

how many parents does asexual reproduction need?

Answer 2

Asexual repro only involves one parent whereas sexual requires two

Question 3

what is a zygote

Answer 3

a fertilised egg cell

Question 4

what type of organisms reproduce asexually 4

Answer 4

plants, fungi, bacteria and body cells reproduce asexually

Question 5

what 3 things happen in asexual reproduction

Answer 5

in asexual reproduction:
1)The cells divide by mitosis

2)There is no fusion of gametes, no mixing of genetic information, and so no variation

3)produces clones –> the offspring are genetically identical to the parents

Question 6

how are gametes formed

Answer 6

Gametes are formed by the cell division meiosis

Question 7

what are gametes

Answer 7

sex cells

Question 8

how many chromosomes do sex cells have (explain)

Answer 8

Each sex cell has half the original number of chromosomes, so that upon fusion, the original chromosome number is restored

Question 9

what are the gametes in plants

Answer 9

In plants, the gametes are egg cells and pollen

Question 10

what does sexual reproduction do to a species

Answer 10

Sexual reprodution introduces variation

Question 11

what does haploid mean

Answer 11

Haploid = (ha-half) a cell with half the number of chromosomes

Question 12

what does diploid mean

Answer 12

Diploid = a cell with the full set of chromosomes

Question 13

what are alleles

Answer 13

Alleles = different forms of the same gene

Question 14

in asexual reproduction is there any variation

Answer 14

In asexual reproduction there is NO variation

Question 15

how many cells does mitosis produce

Answer 15

Where mitosis produces two identical cells,

Question 16

how many cells does meiosis produce

Answer 16

meiosis produces four cells that are different.

Question 17

what happens in meiosis 3

Answer 17

In meiosis:
1)the chromosomes are duplicated so there are four sets of chromosomes, and each chromosome forms a pair of chromatids

2)Cell divides twice to form four gametes each with a single set of chromosomes

3)Gametes contain random mixtures of original chromosomes, which introduces variation

Question 18

visual representation of meiosis

Answer 18

https://www.youtube.com/watch?v=EEeMCNwowJg

Question 19

advantages of meiosis 3

Answer 19

Asexual reproduction is more energy and time efficient as
there’s no need to find a mate or spread gametes
It is also a lot faster and produces large numbers of identical offspring

Question 20

disadvantages of asexual reproduction

Answer 20

if the environment changes and one organism can’t survive, none can (as they are identical)

Question 21

uses of asexual reproduction

Answer 21

Humans use/speed up asexual reproduction to produce large numbers of clones, for example in food production

Question 22

advantage of sexual reproduction

Answer 22

In sexual reproduction, variation means that even if the environment changes, variation will alllow some animals to survive and reproduce –> natural selection

Question 23

name 2 bodies of spores

Answer 23

Toadstools and puffballs are asexual fruiting bodies full of spores

Question 24

what are the mass of thin threads called

Answer 24

Many fungi are made of a mass of thin threads called hyphae that form from the structures we see

Question 25

when do fungi reproduce asexually

Answer 25

When conditions are NOT good, fungi reproduce asexually

Question 26

how do fungi reproduce asexually

Answer 26

two hyphae from different fungi join and their nuclei fuse

Question 27

what is pollination

Answer 27

Pollination = the process in which pollen from one flower must meet the female parts of another flower.

Question 28

how do animals cause pollination?

Answer 28

Animals pollinate - insects, birds and bats --> carry the pollen/ make it easy to get carried by the wind, so plants are adapted to attract them

Question 29

what are the advantages of plants being able to reproduce asexually

Answer 29

Plants being able to asexually reproduce means that even if plants don’t get pollinated, get eaten or are destroyed by frost, new plants can still form

Question 30

where in the human body and what type of reproduction do malarial parasites use

Answer 30

malarial parasites reproduce asexually in human liver cells and blood cells

Question 31

what happens to some parasites when the temperature drops

Answer 31

the drop in temperature from humans to parasites triggers some parasites to sexually reproduce

Question 32

3 reasons why the genome matters

Answer 32

helps us understand inherited/genetic disorders like cystic fibrosis and sickle cell disease --> higher chance of overcoming them linked to increased risk of developed many diseases so helps predict the risk for each individual understanding it helps us learn more about evolution and history - family trees can be traced back using genome sequences

Question 33

what is the backbone of dna made of

Answer 33

DNA backbone is made out of sugar and phosphate

Question 34

whats the monomer of polynucleotide

Answer 34

its monomer is nucleotide

Question 35

whats the name of dnas polymer

Answer 35

DNA is a polynucleotide

Question 36

what would happen if a mutation in a single group of bases were too occur

Answer 36

A mutation in a single group of bases can lead to a change in the protein structure and the way it works

Question 37

what are the steps to protien synthesis

Answer 37

Genes produce a template for protein --> reflects the sequence of bases in DNA, but is small enough to leave the nuclear pores Template leaves the nucleus and binds to the surface of ribosome Cytoplasm has carrier molecules each attached to an amino acid, which attach to the templates in the correct order given by DNA Amino acids are joined together to form a specific protein Carrier molecules continue bringing the specific amino acids in the correct order until template is completed Protein detaches itself from the carrier molecules which detach from the template to be available to pick up more amino acids completed protein chain folds up to form a unique shape which will help it carry out its function

Question 38

what three things make a nucleotide

Answer 38

nucleotide is a part of the backbone with the base attached to it - it is a sugar, a phosphate and a base

Question 39

what is the meaning of phenotype

Answer 39

Phenotype = the physical properties or physical make up of an organism

Question 40

does mutation in the non coding part of the DNA change the phenotype directy

Answer 40

Mutations in the non-coding part of DNA does not directly change the phenotype

Question 41

variants in the DNA cause?

Answer 41

BUT variants in non coding DNA can affect which genes are switched on and off - by changing the genes that are expressed, this can have a big effect on the phenotype

Question 42

when are genes expressed

Answer 42

A gene being expressed is when the protein that this gene codes for is synthesised in the cell

Question 43

does the most of DNA code for protein

Answer 43

Most of DNA doesn’t code for protein

Question 44

what does homozygous mean

Answer 44

Homozygous = when an individual has the same alleles for a characteristic

Question 45

what does heterozygous mean

Answer 45

Heterozygous = when an individual has different alleles for a characteristic

Question 46

what are dominant alleles

Answer 46

Dominant alleles = expressed in the phenotype even if only one is present

Question 47

what are recessive alleles

Answer 47

Recessive alleles = only expressed in the phenotype in the absence of a dominant allele

Question 48

what do sex chromosomes determine in humans

Answer 48

Sex chromosomes determine the sex of the baby

Question 49

what are the sex chromosomes for males

Answer 49

In human males, the chromosomes are different - XY

Question 50

what are the sex chromosomes for females

Answer 50

In human females the chromosomes are the same - XX

Question 51

what is polydactyly

Answer 51

Polydactyly = when some babies are born with extra fingers or toes

Question 52

what type of allele is polydactyly caused by

Answer 52

The most common form on polydactyly is caused by a dominant allele

Question 53

what is cystic fibrosis

Answer 53

Cystic fibrosis = a genetic disorder that produces really thick and sticky mucus, and affects the lungs, the digestive system and the reproductive system

Question 54

what are the effects of cystic fibrosis

Answer 54

The lungs can become clogged - impairing ventilation The pancreas cannot secrete enzymes The small intestine becomes blocked with mucus Many people with cystic fibrosis are infertile

Question 55

how do we treat cystic fibrosis

Answer 55

Treatments for cystic fibrosis: physiotherapy, antibiotics to keep the lungs clear of mucus and infections, enzymes that the pancreas can’t make are replaced, and drugs to thin the mucus

Question 56

what type of allele causes cystic fibrosis

Answer 56

Is caused by a recessive allele

Question 57

steps to Amniocentesis

Answer 57

Two ways to do this: Amniocentesis = Amnio --> taking amniotic fluid (the fluid that the embryo is floating in) Centesis --> centrifuge the fluid this is carried out at 10-15 weeks of pregnancy - the cells taken from centrifuging can then be used for screening

Question 58

steps to cvs

Answer 58

Chorionic Villus Sampling (CVS) = this is carried out between 10 and 12 weeks of pregnancy You take a small sample of tissue from the placenta - this would provide fetal cells that can be used in screening Both of these methods carry risks of miscarriage

Question 59

steps to pre implantaion screening

Answer 59

Pre-implantation technique = Embryos in IVF can be tested before being impanted with the permission of the couple Screening can sometimes give a false positive or a false negative --> leads to the termination of a healthy baby Screening is expensive --> offered to people with genetic disorders in the family history