Inheritance, Variation and Evolution Flashcards

Question

What are the three types of mutation? explain them.

Answer 1

Insertion - when a new base is inserted into the DNA sequence where it shouldn't be. It can have a knock-on effect on the bases to the right of the insertion Deletion - when a random base is deleted from the DNA sequence. They can have a knock-on effect on the bases further down the sequence Substitution - when a random base in the DNA sequence is changed to a different base. This is less likely to have a knock-on effect on other bases.

Answer 2

1) Sexual reproduction is where genetic information from two organisms (mother + father) is combined to produce offspring which are genetically different to either parent. 2) In sexual reproduction, the mother and father produce gametes by meiosis 3) In humans, each gamete is 23 chromosomes - half the number in a normal cell - it does not have 2 of each chromosome, only 1 4) The egg and sperm then fuse together to form a cell with the full number of chromosomes (half from each parent) IMPORTANT: sexual reproduction involves the fusion of male and female gametes. Because there are 2 parents, the offspring contain a mixture of their parents' genes - causing genetic variation.

Answer 3

1) In asexual reproduction, there is only one parent so the offspring will be genetically identical to the parent 2) Asexual reproduction happens by mitosis - an ordinary cell makes a new cell by dividing by two 3) The new cell has exactly the same genetic information (like genes) as the parent - it is a clone 4) Bacteria, some plants, and some animals reproduce asexually IMPORTANT: asexual reproduction only needs one parent. There is no fusion of gametes, no mixing of chromosomes and no genetic variation between parent and offspring.

Answer 4

1) before the cell starts to divide, it duplicates its genetic information, forming two armed chromosomes - one arm of each chromosome is an exact copy of the other arm. After replication, the chromosomes arrange themselves into pairs. 2) In the first division in meiosis the chromosome pairs line up in the middle of the cell 3) the pairs are then pulled apart so each new cell only has one copy of each chromosome. A mix of both the mother and father chromosomes go into each new cell 4) In the second division, the chromosomes line up again in the centre of the cell. The arms of the chromosomes are pulled apart

Answer 5

You get four gametes, each with only a single set of chromosomes in it. Each of the gametes is genetically different from the others because all the chromosomes are mixed together and each gamete only gets half of them, at random.

Answer 6

1) After the two gametes have fused during fertilisation, the resulting new cell divides by mitosis to make a copy of itself. 2) Mitosis repeats many times to produce lots of new cells in an embryo 3) As the embryo develops, these cells then differentiate into the different types of cells of specialised cell to form a whole organism

Answer 7

- offspring has a mixture of two sets of chromosome, so there is variation - variation means that there is a higher chance of some of the offspring surviving a change in environment - Because some offspring are better adapted to the environment, they are more likely to survive and breed successfully, passing the genes on. This is Natural Selection - We can use selective breeding to speed up natural selection. This allows us to produce animals with desirable characteristics. We can also use it to increase crop yield and therefore increase food supply

Answer 8

- only requires one parent - uses less energy - faster than sexual reproduction - many identical offspring can be produced in favourable conditions

Answer 9

1) malaria - malaria is caused by a parasite that is spread by mosquitos. When a mosquito carrying the parasite bites a human, the parasite is transferred. The parasite reproduces sexually when in the mosquito but asexually in the human 2) Many species of fungus - These species release spores which can become new fungi when they land. Spores can be both sexually and asexually produced. 3) Lots of plants - asexual reproduction might be used to produce "runners" (strawberry plants) or sexual reproduction can be used.

Answer 10

- every body cell has 23 pairs of chromosomes (so 46 individual chromosomes) - Male chromosome pair: XY - Female chromosome pair: XX

Answer 11

Also known as a Punnett square. It is a method of showing the possible gamete combinations. You draw it like this: 1) Identify gametes for each parent. 2) Draw the grid based on the number of traits. 3) Fill in the alleles to find possible genotypes. 4) Calculate probabilities to interpret results

Answer 12

It means that this allele is always expressed (visible) if this allele is present

Answer 13

It means that this allele is only expressed if both of the alleles are this recessive one.

Answer 14

The two alleles for a gene are the same

Answer 15

The two alleles for a gene are different

Answer 16

Cystic fibrosis is a genetic disorder, affecting the cell membranes. It results in the body producing a lot of thick sticky mucus in the air passages and in the pancreas. The allele is recessive, so both parents must carry the allele for the child to have the disorder. If somebody carries the allele but has a more dominant allele too, they are a carrier.

Answer 17

Polydactyly is caused by a dominant allele. It is a genetic disorder which causes a child to have extra fingers or toes. It means that the child could have the disorder if one parent carries the defective allele.

Answer 18

- It implies that people with genetic problems are "undesirable", could increase prejudice - There may be a point where everyone wants to screen their embryos so they can pick the most "desirable" one - Screening is expensive

Answer 19

- It will help to stop people suffering - Treating disorders costs the government (and taxpayers) a lot of money - There are laws to stop it going to far (at the moment parents cannot choose the sex of the baby unless for medical reasons)

Answer 20

Medel carried out an experiment with pea plants to show that the height characteristic in pea plants was determined by separately inherited "hereditary units" passed on from each parent. The ratios of tall and dwarf plants in the offspring showed that the unit for tall plants was dominant over the unit for dwarf plants

Answer 21

- Characteristics in plants are determined by "hereditary units" - Hereditary units are passed on to offspring unchanged from both parents, one unit from each parent - Hereditary units can be dominant or recessive

Answer 22

All of today's species have evolved from simple life forms that first started to develop over three billion years ago

Answer 23

Theory of evolution by natural selection - which basically means that the best animals will survive and pass on the successful genes so that over time organisms become more adapted

Answer 24

- his ideas went against religious beliefs - there was a lack of evidence - Darwin could not explain why or how the useful characteristics appeared and were past onto offspring

Answer 25

when all of a species of plant or animal has died - no longer exists on earth

Answer 26

- the environment changes too quickly - a new predator kills them all - a new disease kills them all - they can't compete with new species for food - a catastrophic event happens that kills them all

Answer 27

It is when humans artificially select the plants or animals that are going to breed so that the genes for particular characteristics remain in the population.

Answer 28

- animals that produce more meat or milk - crops with a resistance to disease - dogs with a good temperament - decorative plants with unusual flowers

Answer 29

1) from your existing stock, select the ones with the desired characteristics 2) breed them with each other 3) select the best of the offspring and breed them together 4) continue this process over several generations. The desirable trait gets stronger each time so (eventually) all offspring will have it

Answer 30

it is the number of different alleles (forms of a gene) in a population

Answer 31

It reduces the gene pool. This is because it is inbreeding, and there are risks of health problems linked with this due to the reduced gene pool

Answer 32

to transfer a gene responsible for a desirable characteristic from one organisms' genome into another organism so that it also has the desired characteristic.

Answer 33

This is when a few plant cells are put in a growth medium with hormones, and they grow into new plants - clones of the parent plant. These can be made very quickly, in very little space, and be grown all year round.

Answer 34

- Gardeners can take cuttings from parent plants, and then plant them to produce clones of the parent plant - these plants can be produced quickly and cheaply. This is an older, simpler method than tissue culture.

Answer 35

the sperm from the best male animal can be used to artificially fertilise the egg from the best female animal. The embryo that develops is then split many times (to form clones) before any cells are specialised.

Answer 36

Adult cell cloning involves taking an unfertilised egg cell and removing the nucleus. The nucleus is then removed from an adult body cell and is inserted into the "empty" egg cell. The egg is then stimulated to make it divide. When the embryo is a ball of cells it is implanted into an adult female. It grows into a clone of the original adult body cell. (this was done to create dolly - a cloned sheep)

Answer 37

- reduced gene pool - if we clone humans, there will be unsuccessful attempts - unfair on the child - cloned animals may not be as healthy as normal ones

Answer 38

The remains of organisms from thousands of years ago, which are found in rocks.

Answer 39

- things like teeth, shells and bones do not decay easily so they last a long time when buried. - they are replaced by minerals as they decay, forming a rock like substance - the surrounding sediments turn to rock, but the fossil stays distinct until it is found

Answer 40

- if an organism is buried in a soft substance (like clay), a fossil is formed - the substance hardens around it, and the organism decays, leaving a cast of itself - Things like footprints or root traces are formed this way

Answer 41

- in amber and tar pits there is no oxygen or moisture so decay microbes can't survive - in glaciers, it is too cold for the decay microbes to work - in peat bogs it is too acidic for decay microbes - this means the organism is perfectly preserved

Answer 42

It is the development of a new species

Answer 43

it is where populations of a species are separated. This (and natural selection) means that different populations may have different traits to help it survive. Over time they become different species, and can no longer breed together.

Answer 44

He was a scientist working at the same time as Charles Darwin. He realised that warning colours are used by species to deter predators, and he developed the idea of speciation.

Answer 45

It means they can become resistant to antibiotics quickly, and can spread at high rates.

Answer 46

The process of organising living organisms into groups, but this system has changed over time

Answer 47

1) ARCHAEA - a type of prokaryotic cell 2) BACTERIA - true bacteria 3) EUKARYOTA - broad range of organisms

Answer 48

phylum, class, order, family, genus, species

Inheritance, Variation and Evolution Flashcards

(72 cards)