7.Reproduction

Question 1

What is asexual reproduction

Answer 1

Asexual reproduction is the the production of offspring that does not involve fusion of gametes and forms clones

Question 2

Identify the different methods of asexual reproduction

Answer 2

-binary fission
-fragmentation
-budding
-spore formation
-parthenogenesis
-vegetative reproduction

Question 3

Compare and contrast binary fission with mitosis

Answer 3

Purpose: asexual production vs growth, repair and replacement
Are chromosomes copied by DNA replication? : yes vs yes
Are spindle fibres formed : no vs yes
Does DNA replication and separation of chromosomes happen at the same time? : yes vs no (happens in S phase of interphase)

Question 4

describe fragmentation

Answer 4

When a multicellular organism splits into pieces and each new piece develops into a new organism

Question 5

which organisms use fragmentation

Answer 5

starfish, marine worms and flatworms

Question 6

describe budding

Answer 6

when an organism, such as yeast, forms a growth that develops into a new organism and then breaks off
-division of cytoplasm is unequal

Question 7

which organisms use budding

Answer 7

Yeast and hydra

Question 8

Describe spore formation

Answer 8

spores are haploid cells that can develop into a new organism
-produced by meiosis
-fully developed spores are diploid

Question 9

what organisms use spore formation

Answer 9

bacteria and fungi eg Rhizopus (on mouldy bread)

Question 10

describe parthenogenesis

Answer 10

The development of an egg cell in the absence of fertilisation
-Extra doubling of chromosomes during egg development
-ALL offspring are female (XX)
-used when their is a shortness in males

Question 11

what organisms use parthenogenesis

Answer 11

certain lizards, birds and insects

Question 12

describe vegetative reproduction

Answer 12

The growth of specialised plant tissue such as rhizomes, runners, tubers or bulbs that can grow into a new plant if it becomes separated from the parent plant

Question 13

what organisms use vegetative reproduction

Answer 13

potatoes, ginger, strawberries, onions

Question 14

Disadvantages of Asexual reproduction

Answer 14

-asexual reproduction produces clones, they are genetically identical, so the population has a low genetic diversity this means that if the environment and selection pressures change then all of the population of clones are likely to not survive

Question 15

Advantages of asexual reproduction

Answer 15

-Offspring are genetically identical to parents so are well suited to a stable environment
-does not require a mate

Question 16

what is sexual reproduction

Answer 16

sexual reproduction is the fusion of gametes to produce offspring that are genetically different

Question 17

describe the differences between asexual and sexual reproduction

Answer 17

-genetically identical vs genetically varied offspring
-no fusion of gametes vs fusion of gametes

Question 18

advantages of sexual reproduction

Answer 18

-sexual reproduction allows there to be more genetic variation in the offspring so they are more likely to survive in changing environment with different selection pressures.

Question 19

disadvantages of sexual reproduction

Answer 19

-crossing over in prophase 1 forms gametes, this could break apart beneficial allele combinations, and whilst the gametes will be varied, they may be less likely to survive
-sexually transmitted infections/ diseases can be passed between individuals in the population

Question 20

what is a clone

Answer 20

genetically identical copy of an organism

Question 21

what is cloning

Answer 21

making a genetically identical copy of an organism

Question 22

identify three methods of cloning

Answer 22

-embryo splitting
-somatic cell nuclear transfer
-cuttings

Question 23

purposes of cloning

Answer 23

-mass produce a crop or livestock animal with desirable traits eg. cows that produce a lot of milk or corn with a high yield
-preserve endangered species
-produce genetically identical lab animals which can be used as models for human disease
-reproduce animals that have been genetically engineered to provide human products eg. transgenic cattle were created to produce milk containing particular human protein which may help in the treatment of human emphysema

Question 24

what is embryo splitting

Answer 24

-a form of cloning where an embryo is split
-a farmer splits embryo during in vitro fertilisation, before putting the embryos into surrogate mothers to increase the number of offspring born in each breeding season with favourable traits, this increases the yield and profit for the farmer.
-offspring are all genetically identical to each other but still relied on fertilisation first, before the embryo was split

Question 25

what is somatic cell nuclear transfer

Answer 25

a form of cloning where a somatic cells nucleus is transferred into an egg cell with no nucleus (enucleated)

Question 26

steps for somatic cell nuclear transfer

Answer 26

1. Removing the nucleus from an egg cell
   2.Putting the nucleus from a somatic cell into the egg cell
2. Giving the cell an electric shock to make it divide
3. Implanting the embryo into a surrogate mother sheep (does not need to be related)
4. Cloning by nuclear transfer produces offspring identical to the organism from which the donor somatic cell is taken

Question 27

what are cuttings

Answer 27

a method of cloning in plants that requires no lab equipment or training
-involves planting a root node that has the ability to grow and differentiate into roots and shoots