Variation and reproduction - 2.3

Question 1

Sexual reproduction def

Answer 1

Where two parents reproduce together, passing down one chromosome from each pair, to produce genetically distinct offspring.

Question 2

Asexual reproduction def

Answer 2

Where one parent reproduces on its own, passing down both pairs of chromosomes, producing genetically identical offspring.

Question 3

Advantages of sexual reproduction

Answer 3

Greater variation
Greater response to selection pressures
Greater resistance to parasites

Question 4

Disadvantage of sexual reproduction

Answer 4

Only half a genome is passed on meaning successful genome is disrupted.
Only half the population will be able to produce offspring, meaning that population can grow more slowly.

Question 5

Advantage of asexual reproduction

Answer 5

Can reproduce faster and repopulate an area much faster
Can be effective in narrow stable niches and environments
Vegetative cloning and parthenogenesis will decrease the number of individuals in a species which fail to reproduce.

Question 6

Disadvantage of asexual reproduction

Answer 6

Lacks genetic diversity
Can decrease the chance of surviving selection pressures
Organisms which asexually reproduce will have lower resistance to parasites.

Question 7

Red queen hypothesis link to sexual reproduction

Answer 7

Hosts which sexually reproduce will be more successful since this will increase genetic diversity of offspring, which will allow for the offspring to potentially have alleles which make them resistant to parasites, and increase the chance of survival and passing on genes further.

Question 8

Vegetative cloning

Answer 8

Where a plant will produce a genetically identical copy of itself from a smaller part of the organism.

Question 8

Parthenogenesis

Answer 8

Where a female will reproduce without fertilising their own gamete.

Question 9

Examples of asexual reproduction in eukaryotes

Answer 9

Vegetative cloning and parthenogenesis

Question 10

Parthenogenesis ideal conditions

Answer 10

Cooler climates with low parasite load and density

Question 11

Method of increasing genetic diversity in asexual reproduction

Answer 11

Parthenogenesis allows for asexual reproduction which doesn’t produce an identical clone of the parent, this is due to a haploid gamete forming the zygote.

Question 11

Example of parthenogenesis

Answer 11

Sharks

Question 12

Example of vegetative cloning

Answer 12

Perennial weeds such as onions

Question 13

Advantage of horizontal gene transfer

Answer 13

Allows for evolution occur faster since genes can be passed between organisms of the same generation.

Question 14

Meiosis steps in order

Answer 14

Interphase 1
Prophase 1
Metaphase 1
Anaphase 1
Telophase 1 and cytokinesis
Prophase 2
Metaphase 2
Anaphase w
Telophase

Question 15

Somatic cells definition

Answer 15

Cells that she not gametes

Question 16

Gamete definition

Answer 16

Haploid cells which fuse together to form a zygote.

Question 17

Mitosis steps

Answer 17

Prophase
Metaphase
Anaphase
Telophase
Interphase.

Question 18

Mitosis definition

Answer 18

Where somatic cells divide to form more somatic cells.

Question 19

Interphase

Answer 19

The chromosomes duplicate to form sister chromatids attached at the centromere

Question 20

Centromere definition

Answer 20

The section where two sister chromatids are pulled apart by spindle fibres.

Question 21

Centrioles

Answer 21

Opposite ends of a cell.

Question 22

Prophase 1

Answer 22

The nuclear membrane will be removed and chromosomes will be arranged into homologous partners, chiasmata will be formed and there is the potential for crossing over of sections of chromosomes.

Question 23

Anaphase 1

Answer 23

Chromosomes line up randomly on the metaphasic plate and kinetochores of each chromatid will bind to spindle fibres.

Question 24

Chiasma def

Answer 24

The site in sister chromatids where recombinant strands can be formed from crossing over.

Question 25

Metaphasic plate

Answer 25

The centre line elf the cell where chromatids line up

Question 26

Kinetichores

Answer 26

Sites on sister chromatids where spindle fibres bind

Question 27

Random assortment

Answer 27

Where sister chromatids randomly line up on the metaphasic plate increasing the variation of the daughter cells.

Question 28

Crossing over

Answer 28

Where sections of a chromosome will swap with their homologous partner

Question 29

Anaphase 1

Answer 29

Spindle fibres contract which will pull the homologous chromosomes to opposite poles.

Question 30

Prophase 2

Answer 30

Nuclear membranes formed break down, and centrioles will be duplicated again, spindle apparatus is formed.

Question 30

Metaphase 2

Answer 30

Chromosomes line up on metaphasic plate and spindle fibres will bind to kimetochores

Question 31

Anaphase 2

Answer 31

Sister chromatids are pulled apart to opposite poles forming individual chromosomes

Question 32

Telophase 2

Answer 32

Nuclei form at the poles and cytokinesis occurs (cytoplasm divides) 4 haploid daughter cells are formed.

Question 33

Difference in mitosis and meiosis

Answer 33

Meiosis forms 4 daughter cells Mitosis forms 2 daughter cells. Meiosis forms distinct haploid daughter cells Mitosis forms identical diploid daughter cells.

Question 34

Linked genes

Answer 34

Genes which are inherited together often due to being close together.

Question 35

Meiosis cells type of cell

Answer 35

Somatic cells

Question 36

Independent assortment

Answer 36

Random assortment

Question 37

SRY gene

Answer 37

The gene in the Y chromosome which determines maleness

Question 38

human chromosome break down

Answer 38

23 chromosome pairs consisting of 22 autosome pairs and 1 sex pair

Question 39

Autosomes

Answer 39

Chromosomes which aren’t involved in sex

Question 40

Male sex chromosome combination

Answer 40

XY

Question 41

Female sex chromosomes combination

Answer 41

XX

Question 42

Homogametic

Answer 42

Female -XX

Question 43

Heterogametic

Answer 43

Male - XY

Question 44

Y chromosome length

Answer 44

60 genes

Question 45

X chromosome length

Answer 45

1000 genes

Question 46

Explanation of why males develop genetic conditions more than females

Answer 46

Males contain XY sex chromosomes instead of females XX chromosomes. This female X chromosome is much larger than the males Y chromosome and contains more genes. The male Y chromosome is missing genes that would normally be expressed instead of a faulty gene such as in females.

Question 46

Problem of females XX chromosomes

Answer 46

Homogametic females non homologous section can potentially double dose due to two X chromosomes present. This means that one X chromosome will randomly inactivate. (Random X inactivation)

Question 47

Natural examples of random X inactivation

Answer 47

Tortoiseshell cat

Question 48

Hermaphrodites

Answer 48

Species containing both male and female reproductive organs in one individual.

Question 49

Where are hermaphrodites found

Answer 49

Where it is unlikely to find a reproductive partner - typically in sessile animals and parasites.

Question 50

Sex determination by non genetic means

Answer 50

Population Size, competition, parasitic infection and temperature

Question 51

Temperature effect on sex determination

Answer 51

Some species such as turtles only produce female offspring if incubation occurs above a certain temperature.