Variation and reproduction - 2.3 Flashcards

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1
Q

Sexual reproduction def

A

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

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2
Q

Asexual reproduction def

A

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

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3
Q

Advantages of sexual reproduction

A

Greater variation
Greater response to selection pressures
Greater resistance to parasites

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4
Q

Disadvantage of sexual reproduction

A

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.

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5
Q

Advantage of asexual reproduction

A

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.

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6
Q

Disadvantage of asexual reproduction

A

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

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7
Q

Red queen hypothesis link to sexual reproduction

A

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.

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8
Q

Vegetative cloning

A

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

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8
Q

Parthenogenesis

A

Where a female will reproduce without fertilising their own gamete.

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9
Q

Examples of asexual reproduction in eukaryotes

A

Vegetative cloning and parthenogenesis

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10
Q

Parthenogenesis ideal conditions

A

Cooler climates with low parasite load and density

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11
Q

Method of increasing genetic diversity in asexual reproduction

A

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.

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11
Q

Example of parthenogenesis

A

Sharks

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12
Q

Example of vegetative cloning

A

Perennial weeds such as onions

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13
Q

Advantage of horizontal gene transfer

A

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

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14
Q

Meiosis steps in order

A

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

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15
Q

Somatic cells definition

A

Cells that she not gametes

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16
Q

Gamete definition

A

Haploid cells which fuse together to form a zygote.

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17
Q

Mitosis steps

A

Prophase
Metaphase
Anaphase
Telophase
Interphase.

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18
Q

Mitosis definition

A

Where somatic cells divide to form more somatic cells.

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19
Q

Interphase

A

The chromosomes duplicate to form sister chromatids attached at the centromere

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20
Q

Centromere definition

A

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

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21
Q

Centrioles

A

Opposite ends of a cell.

22
Q

Prophase 1

A

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.

23
Q

Anaphase 1

A

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

24
Q

Chiasma def

A

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

25
Q

Metaphasic plate

A

The centre line elf the cell where chromatids line up

26
Q

Kinetichores

A

Sites on sister chromatids where spindle fibres bind

27
Q

Random assortment

A

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

28
Q

Crossing over

A

Where sections of a chromosome will swap with their homologous partner

29
Q

Anaphase 1

A

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

30
Q

Prophase 2

A

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

30
Q

Metaphase 2

A

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

31
Q

Anaphase 2

A

Sister chromatids are pulled apart to opposite poles forming individual chromosomes

32
Q

Telophase 2

A

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

33
Q

Difference in mitosis and meiosis

A

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

34
Q

Linked genes

A

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

35
Q

Meiosis cells type of cell

A

Somatic cells

36
Q

Independent assortment

A

Random assortment

37
Q

SRY gene

A

The gene in the Y chromosome which determines maleness

38
Q

human chromosome break down

A

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

39
Q

Autosomes

A

Chromosomes which aren’t involved in sex

40
Q

Male sex chromosome combination

A

XY

41
Q

Female sex chromosomes combination

A

XX

42
Q

Homogametic

A

Female -XX

43
Q

Heterogametic

A

Male - XY

44
Q

Y chromosome length

A

60 genes

45
Q

X chromosome length

A

1000 genes

46
Q

Explanation of why males develop genetic conditions more than females

A

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.

46
Q

Problem of females XX chromosomes

A

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)

47
Q

Natural examples of random X inactivation

A

Tortoiseshell cat

48
Q

Hermaphrodites

A

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

49
Q

Where are hermaphrodites found

A

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

50
Q

Sex determination by non genetic means

A

Population Size, competition, parasitic infection and temperature

51
Q

Temperature effect on sex determination

A

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