inheritance, variation and evolution

Question 1

What are the products of mitosis?

Answer 1

The products of mitosis is two identical cells. This is genetically identical offspring.

Question 2

What are the products of meiosis?

Answer 2

The products of meiosis is two non-identical cells.

Question 3

What are the male and female gametes in flowering plants?

Answer 3

The male and female gametes in flowering plants are pollen and egg.

Question 4

Where does meiosis take place?

Answer 4

Meiosis takes place in reproductive organs.

Question 5

Describe the process of meiosis.

Answer 5

meiosis:

1) cell chromosomes are copied
2) cell divides into two and again
3) four gametes, each with a single set of chromosomes
- all gametes are genetically different
- the gametes fuse together to restore 23 pairs of chromosomes

Question 6

What are the advantages of sexual reproduction?

Answer 6

• produces variation in offspring

- if environment changes, variation gives a survival advantage by natural selection

Question 7

What are the advantages of asexual reproduction?

Answer 7

• only one parent needed
• faster than sexual
• more time and energy efficient
• useful when conditions are favourable

Question 8

What is a disadvantage of asexual reproduction?

Answer 8

• when conditions are infavourable, all will die

Question 9

Give three examples of organisms that reproduce by both sexual and asexual reproduction.

Answer 9

• malarial parasites use asexual in a human host, but sexual in the mosquito
• fungi reproduce asexually but sexual for variation
• plants sexually with seeds but asexually for runners or bulb division

Question 10

What is DNA? What is it made of?

Answer 10

DNA is a polymer of two strands forming a double helix. It is made of molecules called nucleotides.

Question 11

What is a gene? What does it code for?

Answer 11

A gene is a small section of DNA. DNA is a molecule in a chromosome. Each gene codes for a particular sequence of amino acids to make a specific protein.

Question 12

What is a genome?

Answer 12

The genome of an organism is the entire genetic material of that organism.

Question 13

Why is it important to understand the human genome?

Answer 13

• for medicine
• to search for genes linked to disease
• understanding and treatment of inherited disorders
• trace human migration patterns from the past

Question 14

What does each nucleotide consist of?

Answer 14

Each nucleotide (what DNA is made of) consists of a phosphate group attached to a sugar molecule attached to a base.

Question 15

What are the four bases possible attached to nucleotides? What is the combination?

Answer 15

The four bases are A, G, C and T.

A + T, G + C

Question 16

What is the code for an amino acid?

Answer 16

The code for an amino acid is a sequence of three bases.

Question 17

What are the two stages of protein synthesis?

Answer 17

protein synthesis:
1) transcription - in nucleus, base sequence of gene is copied into a complimentary template molecule, called mRNA, passed into cytoplasm

2) translation - mRNA attaches to ribosome, ribosomes read triplets of bases to join amino acids into correct order, then folds for unique job

Question 18

How are amino acids transported to the ribosomes?

Answer 18

Amino acids are brought to ribosomes on carrier molecules called tRNA.

Question 19

What are the effects of mutations in protein synthesis?

Answer 19

• most don’t alter the protein
• some slightly alter the appearance but not the function
• few change the shape (eg. enzymes won’t be specific)
• may effect how genes are expressed

Question 20

What are alleles?

Answer 20

Alleles are different versions of a gene.

Question 21

What is the genotype?

Answer 21

Genotype is the alleles present.

Question 22

What is homozygous?

Answer 22

Homozygous is two copies of the same allele.

Question 23

What is heterozygous?

Answer 23

Heterozygous is two different copies of an allele.

Question 24

What is the phenotype?

Answer 24

Phenotype is the characteristics caused by an allele.

Question 25

What is a dominant allele?

Answer 25

The dominant allele is always expressed, even if there is only one of it.

Question 26

What is a recessive allele?

Answer 26

The recessive allele is only expressed when two copies are present.

Question 27

What is cystic fibrosis? Is it dominant or recessive?

Answer 27

Cystic fibrosis is a disorder of the cell membrane. It is recessive.

Question 28

What is polydactyly? Is it dominant or recessive?

Answer 28

Polydactyly is a disorder of having extra fingers or toes. it is dominant.

Question 29

What is embryo screening? What are the positives and negatives?

Answer 29

Embryo screening is when embryos are tested to see if they have alleles for inherited disorders, and ones that don't are implanted into the woman. It is expensive, unethical and in the future, we can screen for desirable features.

Question 30

What is gene therapy?

Answer 30

Gene therapy will be used in the future, which will be correcting faulty genes.

Question 31

What are the chromosomes that determines sex?

Answer 31

In women, XX pair. | In men, XY pair.

Question 32

What is variation?

Answer 32

Variation is all of the differences in characteristics of individuals in a population.

Question 33

What are the three main causes of variation?

Answer 33

- the genes they have inherited - the environment - combination of genes and environment

Question 34

What is evolution?

Answer 34

Evolution is a change in the inherited characteristics of a population over time through natural selection.

Question 35

Describe the process of natural selection.

Answer 35

1) variation caused by a random mutation 2) competition for food, water and land 3) the better adapted species outlive 4) they pass on the genes 5) over time, all of the population has these traits

Question 36

What is selective breeding?

Answer 36

Selective breeding is the process by which humans breed plants and animals for particular genetic characteristics.

Question 37

What are four uses of selective breeding?

Answer 37

- domestic dogs with a gentle nature - large or unusual flowers - disease resistance in food crops - animals which produce more meat or milk

Question 38

Describe the process of selective breeding.

Answer 38

1) choose parents with desired characteristics 2) breed them 3) breed offspring with desired characteristic 4) continue until all offspring show desired characteristic

Question 39

What are GM crops? How are they beneficial and harmful?

Answer 39

GM crops are genetically modified crops. They can be used for increased yields and resistance. They could be harmful to insects and wild flowers, but the effects on humans eating them needs more research.

Question 40

Describe the process of genetic engineering.

Answer 40

1) identify the gene we want to transfer 2) use enzymes to isolate the genes 3) transfer the gene into a vector (usually bacterial plasmid or a virus) 4) the gene is inserted into the required cells

Question 41

In genetic engineering, why must you always transfer the gene at an early stage in the organism's development?

Answer 41

You must always transfer the gene at an early stage in the organism's development so that they develop with the characteristics.

Question 42

How can we clone plants via cuttings?

Answer 42

cloning plants via cutting: - an older, simple method - take small cutting and dip end in rooting powder to encourage the development of roots - only works if we want a few clones

Question 43

How can we clone plants via tissue culture?

Answer 43

cloning plants via tissue culture: - using a small group of cells from part of a plant - important for preserving rare species or commercial plant nurseries

Question 44

How can we clone animals via embryo transplants?

Answer 44

cloning animals via embryo transplants: - split apart cells from a developing embryo before they become specialised and insert each into mother - cannot be certain they will have the desired characteristics

Question 45

Describe the process of adult cell cloning.

Answer 45

1) remove nucleus from somatic (body) cell 2) remove nucleus from egg cell 3) insert nucleus from somatic to egg cell 4) give the egg cell an electric shock to divide embryo 5) when the embryo is a ball of cells, insert into female - produces clone of somatic cell - we know the characteristics the clone will have

Question 46

Who developed the theory of natural selection?

Answer 46

Charles Darwin developed the theory of evolution when he traveled around the world and made observations.

Question 47

When did Darwin publish his theory of evolution? Why was it not accepted at the time?

Answer 47

Darwin published his theory in 'On the Origin of Species' in 1859. It wasn't accepted at the time as: - it challenged God - there was insufficient evidence - people didn't know about inheritance

Question 48

What did Jean-Baptiste Lamark suggest?

Answer 48

Jean-Baptise Lamark suggested that when a characteristic is regularly used, it becomes more developed. We now know that changes in an organisms lifetime is not inherited.

Question 49

What did Alfred Russel Wallace suggest?

Answer 49

Alfred Russel Wallace independently proposed his idea of natural selection, so him and Darwin proposed their joint findings in 1858. He is also known for his work on warning colouration in animals and his theory of speciation.

Question 50

Describe the process of speciation.

Answer 50

Speciation is the formation of new species. 1) there is a geographical barrier to split up a species 2) each side adapts to their environment 3) they become so different that they can no longer interbreed

Question 51

What did Gregor Mendel do? What were his observations?

Answer 51

Gregor Mendel carried out breeding experiments on plants. - observed that characteristics are determined by units that are passed onto descendants unchanged - discovered dominant and recessive alleles - proved correct when in late 19th century, scientists looked at chromosomes in cell division

Question 52

What are fossils?

Answer 52

Fossils are the remains of organisms from millions of years ago.

Question 53

How might fossils be formed?

Answer 53

- parts of organisms haven't decayed because one or more of the conditions for decay were absent - parts of organisms are replaced by minerals as they decay - preserved traces of organisms (footprints)

Question 54

Why is it hard to know how life began? (fossils)

Answer 54

It is hard to know how life began because many early life forms were soft bodied so they left very few traces. What traces were left have been mainly destroyed by geological activity.

Question 55

What are four ways that species can become extinct?

Answer 55

- a catastrophic event - environmental changes - a new disease or predator - a new, more successful species competes

Question 56

How quickly can bacteria reproduce?

Answer 56

Bacteria can reproduce up to every 30 minutes.

Question 57

Describe the process of how resistant bacteria form.

Answer 57

resistant bacteria: 1) mutations cause new strains, which may be resistant 2) they survive and reproduce 3) the resistant strain will spread so the people will have no effective treatment

Question 58

Name a strain of bacteria resistant to antibiotics.

Answer 58

MRSA is a strain of bacteria resistant to antibiotics.

Question 59

What are three ways to reduce bacterial resistance?

Answer 59

- doctors should not prescribe antibiotics inappropriately - patients should complete the course of their antibiotics so all the bacteria are killed - restrict use of antibiotics in farming

Question 60

Why are resistant strains of bacteria so dangerous?

Answer 60

Resistant strains of bacteria are so dangerous as developing new antibiotics is costly and slow, so it is unlikely people will keep up with the emergence of new strains.

Question 61

What is the order for classifying organisms that Carl Linnaeus discovered?

Answer 61

``` Kingdom Phylum Class Order Family Genus Species ```

Question 62

How are organisms named?

Answer 62

Organisms are named by the binomial system. | genus-species

Question 63

What system did Carl Woese develop for classifying organisms?

Answer 63

Carl Woese developed the three domain system. archaea (primative bacteria, usually in extreme environments) bacteria (true bacteria, like in digestive system) eukaryota (protists, fungi, plants, animals)