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biology > D3.1 - reproduction > Flashcards

D3.1 - reproduction Flashcards

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1
Q

chemotaxis

A

movement in response to a chemical signal

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2
Q

fertilisation

A

fusion of gametes

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3
Q

morphology

A

study of the form and structure of organisms

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4
Q

what is the role of meiosis in the sexual life cycle?

A
  • breaks up the parental combination of alleles
  • produces haploid gamete cells in a reduction division, meaning only half the genes for a parent can be passed onto the offspring
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5
Q

what is the role of fertilisation in the sexual life cycle?

A
  • produces a new combination of alleles
  • fusion of haploid gametes nuclei restores the diploid number of chromosomes as homologous pairs with 1 coming from the male parent and 1 coming from the female parent
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6
Q

what are the characteristics of sexual reproduction?

A
  • involves 2 parents
  • fusion of male and female gametes
  • new allele combination which leads to genetic variation in the offspring, unique to both parents
  • cell division involves meiosis
  • chromosome numbers are halved during gamete formation and re-established during fertilisation
  • usually slower and requires more energy
  • new allele combination provides variation needed for adaption to the changed environment
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7
Q

what are the characteristics of asexual reproduction?

A
  • involves 1 parent
  • no fusion of gametes
  • no new allele combinations , so offspring are genetically identical to the parent
  • cell division involves mitosis or binary fission
  • chromosome numbers are maintained throughout
  • usually faster and requires less energy
  • production of genetically identical offspring allows colonization by individuals that are already adapted to the existing environment
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8
Q

what are the characteristics of males in sexual reproduction?

A
  • gamete is small and motile to efficiently move to the female gamete
  • gamete has less food reserves
  • releases millions of gametes
  • males typically mate with females as they aren’t involved in parental care and breeding success is often based on having large numbers of offspring
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9
Q

what are the characteristics of females in sexual reproduction?

A
  • gamete is large and immotile
  • gametes contain enough nutrients to support early development of the embryo
  • females tend to choose mates with particular traits that indicate health and ability to provide support and breeding success is based on the quality of parental care
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10
Q

what are the components of the female reproductive system?

A
  • ovary
  • oviduct
  • uterus
  • endometrium
  • cervix
  • vagina
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11
Q

what are the components of the male reproductive system?

A
  • vas deferens
  • seminal vesicle
  • prostate gland
  • epididymis
  • urethra
  • testis
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12
Q

what is the function of the ovary?

A

where oocytes mature prior to ovulation and from where oestradiol and progesterone are secreted into the bloodstream

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13
Q

what is the function of the oviduct?

A

transports the oocyte/early embryo from the ovary to the uterus

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14
Q

what is the function of the uterus?

A

the muscular organ where the early embryo implants and develops

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15
Q

what is the function of the endometrium?

A

vascular inner lining of the uterus wall

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16
Q

what is the function of the cervix?

A

muscular opening, allowing the sperm to enter and a route for childbirth

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17
Q

what is the function of the vagina?

A

muscular passage leading from the external genitalia to the uterus, where semen is released during sexual intercourse

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18
Q

what is the function of the vas deferens?

A

muscular duct which transports the sperm from epididymis to the urethre during ejaculation

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19
Q

what is the function of the seminal vesicle?

A

gland that contributes to the formation of semen, providing fluid for the sperm

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20
Q

what is the function of the prostate gland?

A

secretes an alkaline fluid to neutralise vaginal acids and maintain sperm viability

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21
Q

what is the function of the epididymis?

A

where sperm matures and becomes motile and is stored until ejaculation

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22
Q

what is the function of the urethra?

A

conducts sperm and semen outside the body through the penis during ejaculation

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23
Q

what is the function of the testis?

A

produces sperm, within the seminiferous tubules, and secretes testosterone into the bloodstream

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24
Q

where does fertilisation occur?

A

oviduct

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25
Q

what is the process of fertilisation?

A

1) sperm enter the oviduct and move towards the eff due to chemotaxis.
2) acrosome reaction allows sperm to penetrate the zona pellucida.
3) one sperm’s plasma membrane fusses with the egg’s plasma membrane.
4) the sperm’s nucleus enters the egg, while vesicles released from the egg destroy the sperm tail and mitochondria.
5) the egg nucleus completes meiosis II.
6) dissolution of the nuclear membrane of the sperm and egg nuclei.
7) all the condensed chromosomes from the egg and sperm undergo a joint mitosis to produce 2 diploid nuclei.

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26
Q

what 2 cycles makes up the menstrual cycle?

A
  • ovarian cycle
  • uterine cycle
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27
Q

what are the events in the ovarian cycle?

A

1) Constant development of early-stage follicles.
2) selection of a follicle, containing a maturing oocyte (egg).
- stimulated by a lack of progesterone and the presence of FSH.
3) ovulation - release of the egg from the ovary to the oviduct.
- stimulated by LH
4) empty outer ring of follicle cells becomes corpeus luteum and releases progesterone.
5) corpeus luteum degrades after 10-12 days.

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28
Q

what is the corpeus luteum?

A

temporary collection of cells that forms on your ovary each menstrual cycle if you’re still getting a menstrual cycle
- it appears right after ovulation and ensure your uterus is a healthy place for a fetus to grow.

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29
Q

what are events in the uterine cycle?

A

1) menstruation - loss of the endometrium (uterus lining)
- lack of progesterone
2) repair and development of the endometrium (uterus lining)
- stimulated by oestradiol
3) thickening of the endometrium
- stimulated by progesterone
4) maintenance of the endometrium
- stimulated by progesterone

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30
Q

what is the role of LH?

A

Luteinizing hormone
- LH peaks trigger ovulation; the oocyte is released from the follicle.
- LH triggers development of the corpeus luteum, which secretes progesterone.

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31
Q

what is the role of FSH?

A

Follicle stimulating hormone
- stimulates development of the follicles in the ovary (egg maturation)
- follicle cell division produces oocytes
- follicles release oestradiol

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32
Q

what is the role of progesterone?

A
  • stimulates thickening and maintenance of the endometrium (preparing for implantation)
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33
Q

what is the role of oestradiol?

A
  • stimulates repair and development of the endometrium.
  • stimulates production of more FSH receptors on follicle cells, so they responds more strongly to FSH.
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34
Q

what hormones are produced in the pituitary gland?

A

FSH and LH

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35
Q

what hormones are produced in the ovaries?

A

Oestradiol and Progesterone

36
Q

which hormones act on the ovaries?

A

FSH and LH

37
Q

which hormones act on the uterus?

A

Oestradiol and Progesterone

38
Q

what is a negative feedback cycle?

A

response that prevents the system from fluctuating outside of a set range

39
Q

what is a positive feedback cycle?

A

a process that amplifies a response

40
Q

what is the relationship with LH and oestradiol?

A
  • Negative feedback cycle
  • LH inhibits follicle cell development and oestradiol secretion
41
Q

how does LH affect the corpeus luteum?

A
  • triggers development of the corpeus luteum, which secretes progesterone.
42
Q

what is the relationship between progesterone and FSH / LH?

A
  • Negative feedback cycle
  • progesterone causes the pituitary gland to inhibit secretion of FSH and LH.
43
Q

what does the falling levels of progesterone at the end of the cycle trigger?

A
  • menstruation
  • FSH production to restart (due to a lack of inhibition by progesterone)
44
Q

what occurs to hormones if the egg is fertilized and you are pregnant?

A
  • progesterone is continually being releases, which inhibits FSH and LH.
45
Q

what is the relationship between high concentrations of oestradiol and LH / FSH?

A
  • Negative feedback cycle
    high oestradiol concentrations:
  • stimulates LH production
  • inhibits FSH secretion
46
Q

what is the relationship between oestradiol and FSH?

A

Positive feedback cycle
- increase in FSH receptors stimulates follicle development and more oestradiol is released

47
Q

what is the relationship between low concentrations of oestradiol and FSH?

A
  • Positive feedback cycle
  • low oestradiol concentration stimulates FSH production
48
Q

what is the relationship between FSH and oestradiol?

A

Indirect positive feedback
- FSH stimulates oestradiol secretion

49
Q

which menstrual hormones are involved in a positive feedback cycle?

A
  • FSH and oestradiol (indirect)
  • Oestradiol and FSH ( low concetrations)
  • Oestradiol and FSH receptors
50
Q

which menstrual hormones are involved in a negative feedback cycle?

A
  • LH and Oestradiol
  • Progesterone and FSH/LH
  • Oestradiol and FSH (inhibition) and LH (secretion) at high concentrations
51
Q

what is IVF?

A

In Vitro Fertilisation - where sperm and egg cells are collected and fertilised in the lab, and the resulting embryo is implanted into the uterus.

52
Q

what is superovulation?

A

when multiple eggs mature at once

53
Q

what is the role of drugs and hormones in IVF?

A

drugs are used to suspend the normal secretion of hormones, followed by the use of artificial doses of hormones to induce super ovulation and establish a pregnancy.

54
Q

what hormones would be needed to induce superovulation and why?

A

FSH - to stimulate maturation of several eggs in 1 cycle.
LH - to stimulate ovulation and the formation of the corpeus luteus

55
Q

which hormones would be needed to establish pregnancy and why?

A

Progesterone to:
- thicken and maintain the endometrium (uterus lining), ready for implantation
- prevent menstruation

56
Q

What are the elements of a flower reproductive system?

A

Anther, Filament, Septal, Nectary, Petal, Stigma, Style, Ovary

57
Q

What is the role of the anther?

A

Produces and releases the pollen grains, which contain the male nuclei

58
Q

What is the role of the filament?

A

Holds up the anther

59
Q

What is the role of the petal?

A

Colorful to attract pollinating insects

60
Q

What is the role of the stigma?

A

Sticky region that receives the pollen

61
Q

What is the role of the style?

A

Supports the stigma

62
Q

What is the role of the nectary?

A

Produces sweet nectar to attract pollinating insects

63
Q

What is the role of the ovary?

A

Containing ovules, where the female nuclei develop

64
Q

What is the role of the sepal?

A

Protects the developing flower, while it is in the bud

65
Q

What is the process of sexual reproduction in flowering plants?

A

1) Production of haploid gametes using meiosis.
- Ovules (female gametes) are produced in the ovary
- Pollen grains (male gametes) are produced in the anthers
2) Pollination - transfer of pollen between flowers from anther to stigma
3) The pollen grain grows into a structure called a pollen tube, which penetrates down the style
4) The pollen tube delivers the male reproductive nuclei to the female nuclei within the ovules inside the ovary of a flower
5) Fertilization - fusion of male and female nuclei to produce an embryo
6)Seed develops from fertilized ovule, while fruit develop from the whole ovary
7) Seed dispersal - seeds are distributed away from the parent plant via self-explosion, wind or animals
8) Seeds germinate when conditions are appropriate

66
Q

What is pollination?

A

Transfer of pollen between flowers from anther to stigma

67
Q

What is seed dispersal?

A

Movement of seeds away from the parent-plant via self-explosion, wind or animals

68
Q

What is fertilization?

A

Fusion of male and female nuclei to produce an embryo

69
Q

What is germination?

A

Growth and development of the embryo, and the mobilization of food reserves

70
Q

What does hermaphroditic mean?

A

Contains both male and female structures and is able to fertilise itself can reproduce

71
Q

What impact does self-pollination have on a plant species?

A

Self-pollination leads to interbreeding, which decreases genetic diversity and vigour (healthy growth) in an organism

72
Q

What is cross-pollination?

A

Cross pollination - transfer of pollen produced on one plant to another

73
Q

What is the impact of cross-pollination?

A

Cross pollination increases genetic variation within a species, by preventing self-pollination

74
Q

What are 4 methods of preventing self-pollination?

A
  • Different maturation times for pollen and stigma or ovules
  • Genetic mechanisms where protein interactions occur when pollen lands on the stigma within the same plant, preventing reproduction from continuing in a variety of different ways
  • Having separate male and female flowers on a plant
  • Having separate male and female plants within a species
75
Q

What are the roles of wind pollination?

A
  • Often transfers pollen away from a parent plant
  • Animal pollinators are not needed, an no pollen is eaten by those animals
76
Q

What are the roles of insect pollination?

A

1) Glands in the nectary at the base of the ovary in a flower secrete sugary liquid that attracts pollinators
2) Pollen from the anther sticks to the animal when it enters the flower.
3) Pollen is received by the sticky stigma on the same or another flower.
- Mutualistic relationship as the animal gets nectar and the flower gets pollinated.

77
Q

What are key features of pollination?

A
  • Movement of pollen, containing male gametes
  • Movement from anther to stigma
  • Necessary for fertilization and sexual reproduction
  • If animals eat the pollen, it gets destroyed
78
Q

What are key features of seed dispersal?

A
  • Movement of seeds, contained within fruits
  • Movement away from the parent plant
  • Necessary for germination and colonization of a new area, avoiding intraspecific competition for nutrients
79
Q

What are similarities between pollination and seed dispersal?

A
  • Movement can involve self-explosion, wind or animals
  • Animals may assist movement through pollen/seeds sticking to their fur
  • Animals may be attracted through sweetness and colour (to petals/fruit)
80
Q

What are the requirements of the correct conditions to allow germination to occur?

A

1) Water - rehydrates the seeds, causing swelling and bursting of testa (seed coat)
2) oxygen - used in aerobic respiration to produce energy
3) Suitable temperature - enzyme-catalysed reactions require warmth to increase kinetic energy and the rate if molecule collisions
4) Suitable pH of soil - prevents denaturation of the enzymes that control the metabolic events of germination

81
Q

What are the structures within a starchy seed from an external view?

A
  • Testa
  • Micropyle - scar where the pollen tube entered the ovule at fertilization
  • Hilum - where the seed was attached to the ovary wall
82
Q

What are structures within a starchy seed from an internal view?

A
  • Testa - tough, protective outer coat
  • Radicle - embryonic root ending in an apex
  • Plumule - embryonic shoot with embryonic leaves
  • Cotyledon - seed leaf for nutrient storage
83
Q

What are the metabolic events of germination in a typical starchy seed?

A

1) Water is absorbed through the micropyle to rehydrate the seed.
2) This activates metabolism, causing the hormone gibberelic acid to be produced in the embryo, which stimulates the production of amylase.
3) This enzyme catalyses the breakdown of starch to maltose.
4) The maltose diffuses to the embryo root (radicle) and shoot (plumule) where it is hydrolysed to glucose and used to release energy through aerobic respiration and converted to a range of biological molecules to be used for growth.
5) Growth and development of the embryo occurs;
- growth of the radicle downward
- growth of the plumule upwards
- cotyledons are raised
- a true leaf emerges between the cotyledons, allowing photosynthesis to occur to further support growth and development

84
Q

Why does the embryonic plant lose biomass?

A

Initially, the dry mass of a plant embryo decreases over time, because the rate of respiration is higher than that of photosynthesis

85
Q

In what conditions is a plant no longer considered to be embryonic?

A

Once the rate of photosynthesis exceeds the rate of respiration, the plant gains dry mass and it is no longer considered an embryo

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