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Biology (N.A.) > UNIT 16 Reproduction > Flashcards

UNIT 16 Reproduction Flashcards

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1
Q

asexual reproduction

A

a process
resulting in the production of genetically
identical offspring from one parent

MITOSIS used for asexual repr.

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2
Q

in asexual :

A
  • no fusion of gametes so no mixing of genetic info
  • produces CLONES
  • no genetic variation in offspring
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3
Q

the advantages and disadvantages of
asexual reproduction:

a) to a population of a species in the wild
b) to crop production

A

adv:
- faster
- requires less energy

  • Specifically in crop plants, asexual reproduction means that a plant that has good characteristics (high yield, disease-resistant, hardy) can be made to reproduce asexually and the ENTIRE CROP SHOWS SAME CHARACTERISTICS
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4
Q

disadv! of asexual

A
  • offspring all genetically identical. reproduction does not produce genetic variation
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5
Q

examples

A

bacteria [asexual]

fungi [both]

small plants [both]

& animals [sexual]

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6
Q

sexual reproduction

A

a process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are genetically different from each other

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7
Q

in sexual rep.

A

gametes formed by MEIOSIS, a type of cell division which produces cells with half the chromosome number

zygote DIVIDES by MITOSIS

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8
Q

fertilisation

A

the fusion of the nuclei of
gametes, combining 23 chromosomes in sperm & 23 in egg resulting in a zygote with 46 chromosomes

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9
Q

nuclei of gametes are ____________ and that
the nucleus of a zygote is ____________

GAMETES HIPLOID GAMETES HIPLOID
ZYGOTE DIPLOID ZYGOTE DIPLOID

A

nuclei of gametes/GAMETES are HAPLOID and that
the nucleus of a zygote is DIPLOID

[haploid - contain only one set of chromosomes, in humans 23 chromos.
diploid - cell that contains two sets of chromosomes, one from each parent]

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10
Q

SEXUAL REPR. - adv:

A

adv:
- increases genetic variation
- species can adapt to new environments due to variation, giving them a survival advantage
- disease less likely to affect population due to variation

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11
Q

disadv:

A
  • takes time and energy to find mates
  • difficult for isolated members of the species to reproduce
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12
Q

pollination

  • DEFINE
A

the transfer of pollen
grains from an anther to a stigma

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13
Q

the characteristics of an organism determined by both its environment and genes

asexual reproduction involves one parent and produces genetically identical offspring called clones

sexual reproduction involves two parents and the production of gametes which join together at fertilisation. This mixing of genetic info leads to variations in the offspring

Thee is far more genetic variety in sexual reproduction than in asexual, but sexual repr. is more risky because the organism must find a suitable mate

A
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14
Q

adv of genetic variation in wild

A
  • genetic variation means that organisms can better survive changes to the environment
  • some individuals may die but as the population is genetically diverse some will have the traits to survive
  • prevents extinction
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15
Q

adv in crops

A

Having crop plants that are genetically different to one another is important for ensuring the crop can survive environmental change

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16
Q

stamen [anther, filament]

A

male reproductive organs of plant

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17
Q

carpel [stigma, style, ovary]

A

female reproductive organs of plant

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18
Q

filament [long, thin]

A

elevates anther exposing to wind and pollinators

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19
Q

anther

A

contains/produces and releases pollen (male gamete/sex cell)

male gamete is INSIDE the pollen grain

  • hang outside the flower on long filaments so that wind can catch the pollen
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20
Q

ovary

  • houses ovules; becomes fruit
A

produces ovules (female gamete)

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21
Q

sepal

A

thick protective leaves on outside of bud, peel back after flower blooms

protects unopened flower

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22
Q

receptacle

A

connects stem to flower

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23
Q

style [FEmale]

  • long tube connecting stigma to ovary
A

elevates stigma, exposing to wind and pollinators

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24
Q

stigma [FEmale - top of the female part of the flower]

  • sticky opening
A

catches pollen/collects pollen grains from wind and pollinators

  • stigmas extend outside the flower and are often feathery to allow them to catch wind-borne pollen easily
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25
Q

petals

A

attract pollinators - birds, bees
colours attract them

brightly coloured in insect-pollinated flowers to attract insects

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26
Q

ovule

  • develops female gametes; become seeds
A

contains female sex cells
found inside ovary

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27
Q

flowering plants reproduce …

A

sexually

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28
Q

cross pollination

A

the transfer of pollen from the anther to the stigma of a flower on another plant of the same species

  • increases genetic variation
  • increasing capacity to respond to changes in the environment, less reliance on pollinators
29
Q

self pollination

A

the transfer of pollen from the anther to the stigma of the same flower or another flower on the same plant

30
Q

Self-incompatibility - [NOT ON SYLLABUS]

A

proteins on the surface of pollen grains prevent them from germinating on genetically identical flowers

31
Q

how to predict pollinator

A

through characteristics of a plant’s flower

32
Q

e.g. of characteristics

  • [just for understanding]
A

Flowers have:

  • large, showy petals
  • bright colours and distinctive patterns
  • nectar guides
  • attractive odours

Flowers can be:
- arranged in groups
- located apart from foliage

33
Q

Colour: bee-pollinated

A

Flowers tend to be yellow, blue, purple or white because bees can see these colours.

Bees can also see ultra-violet pigments that may be present in flowers of any colour.

34
Q

bee-pollinated

A
  • Bright and attractive petals
  • Often scented to attract pollinator
  • anther;; Less anthers, usually held inside flower
  • stigma;; Small and sticky – held inside flower
35
Q

WIND-pollinated

A

small and plain

often green

no showy petals, odours or nectar. saves on energy and resources

Lots of pollen produced

36
Q

in wind-pollinated,

& the stigmas are

anthers…

in general, plants grow…

flowers held…

A

stigmas are feathery and sticky and hang out of the flower in the air currents.

  • Anthers dangle loosely on long filaments and can move freely in the wind.
  • Plants grow together in large populations of the same species in an open environment which improves the chances of pollination.
  • Flowers held above or below foliage to be more exposed to the wind.
37
Q

Wind-borne pollen [ON SYLLABUS]

A

dry, not sticky ++ very small and light ;; adapted to be carried large distances.

smooth or dimpled for aerodynamic flight

Produced in large amounts

38
Q

pollen adaptations - INSECT pollinated

A

Sticky/Patterned – adapted to stick to pollinator.

Small amounts produced.

Heavier.

39
Q

Investigate and describe the environmental
conditions that affect germination of seeds,
limited to the requirement for: water, oxygen and a suitable temperature

A
40
Q

Fertilisation occurs after… when…

A

occurs after pollination when a pollen nucleus fuses with an ovule nucleus

41
Q

process -

Describe the growth of the pollen tube and its entry into the ovule followed by fertilisation

A
  1. pollen grows a pollen tube down the style
  2. the nucleus inside the pollen grain moves down the tube towards the ovule
  3. after fertilisation a zygote has been formed which will develop into a seed
42
Q

ADDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD NOTES ABOUT SEXUAL REPRODUCTION IN PLANTS AND SEXUAL HORMONES

A
43
Q

describe a STI as…

[used to be STDs, HIV human immunodeificiency virus causing AIDS acquired immunodeficiency syndrome]

A

an infection that is transmitted through sexual contact

44
Q

what is HIV

A

human immunodeficiency virus (HIV)
is a pathogen that causes an STI

  • HIV infection may lead to AIDS
45
Q

methods of transmission of HIV

A
  • use of non-sterile syringes and tools
  • pregnancy. breastfeeding
  • blood transfusion
  • organ transplant
  • UNPROTECTED sex
46
Q

AIDS

A
  • weakens immune system, leaves person at risk of death from other pathogens
47
Q

how the spread of STIs is controlled

A
  • use a condom during sex
  • do not share needles for injecting drugs
  • avoid breastfeeding if you are HIV-positive
  • Get tested for STIs. Make sure you check if someone has an STI before sex. Make sure you trust them - some people may lie or try to pressure you.
48
Q

female reproductive system

  1. production of gametes
  2. site of implanation
  3. site of fertilisation
  4. dilates during birth
A
  1. ovary T
  2. uterus X
  3. fallopian tube R
  4. cervix V
49
Q

state meanings of
1. pollination
2. fertilisation

A
  1. transfer of pollen grains from the anther to the stigma
  2. gametes fuse
    pollen nucleus fuses with a nucleus in an ovule
50
Q

desc 2 implications of self-pollination

A

less variation ;

less chance for adaptation to new environment ;

more chance to pass on genetic disease ;

single plant can reproduce ;

well adapted to environment ;

more chance of fertilisation ;

whole crop would be susceptible to adverse factors like disease ;

51
Q

Sexual hormones - difference between primary sexual characteristics & secondary

A

primary: present during development in the uterus and are the differences in reproductive organs etc between males and females

Secondary sexual characteristics = the changes that occur during puberty as children become adolescents; controlled by the release of hormones - oestrogen in girls and testosterone in boys

  • both: growth of sexual organs and growth of body hair, emotional changes (i.e. more interest in sex and increased mood swings)
52
Q

females

A

-breasts develop
-body hair grows
menstrual cycle begins
-hips get wider

53
Q

males

A

-growth of penis & testes
-growth of facial & body hair
-muscles develop
-voice breaks
-testes start to produce sperm

54
Q

menstrual cycle

A
  • ~12 yrs, cycle takes 28 days. lasts around 5 - 7 days; signals beginning of cycle
  • controlled by hormones
  • during this cycle, uterus lining becomes THICKER in prep for an embryo potentially implanting
  • no implantation in cycle = lining is shed/broken down during menstruation & cycle repeats
  • after menstruation finishes, lining of the uterus starts to thicken again in preparation for possible implantation in the next cycle
55
Q

ovulation - when does this occur (release of an egg)

A

occurs about halfway through the cycle (day 14) and the egg then travels down the oviduct to the uterus

56
Q

menstruation is when in cycle

A
  • menstruation is in the first 7 days of the cycle
57
Q

FSH, follicle stimulating hormone (from pituitary gland)

A
  • stimulates egg maturation in the follicles of the ovary, makes follicle mature
  • stimulates follicles in the ovaries to secrete oestrogen
58
Q

LH luteinising hormone

A
  • at its peak, stimulates ovulation (release of egg into OVIDUCT)
  • results in formation of a corpus luteum
59
Q

oestrogen

A
  • stimulates the uterus to develop a lining (to replace the lining lost during menstruation)
  • post-ovulation, inhibits FSH and LH production in the pituitary gland
60
Q

progesterone

A
  • maintains & thickens lining of the uterus
  • inhibits FSH and LH production
  • if fertilisation doesn’t occur, levels drop & menstruation occurs
61
Q

if fertilisation and implanation DOES occur…

A
  • the corpus luteum will remain producing progesterone and keeping the uterus lining thick
  • if fertilisation does NOT occur, the corpus luteum will break down, stopping the production of progesterone and causing menstruation
62
Q

desb what happens at ovulation

A
  • release of an egg into oviduct
63
Q

name cell produced at fertilisation by fusion of 2 gametes

A

zygote

64
Q

exam ques - ordering some events that occur in the menstrual cycle

secrete FSH ➡ follicles develop in ovary ➡ oestrogen from follicle cells ➡ repair&growth of uterine lining + stops FSH ➡ LH from pituitary gl. ➡ ovulation

A

H: FSH is secreted by pituitary gland

K: 1 or more follicles start to develop in an ovary

M: oestrogen is secreted by follicle cells

J: oestrogen stimulates repair & growth of the lining of the uterus

O: oestrogen inhibits secretion of FSH

N: LH is secreted by the pituitary gland

L: ovulation occurs

65
Q

germination (seed sprouting)

requires THREE factors:

A

📌 water (needed to soften seed)

📌 suitable temperatures (makes sure it is the right time of year to sprout)

📌 oxygen (needed for respiration to produce energy for cell division)

66
Q

desc what happens to structures to bring about fertilisation [3]

A

(stigma) is where pollen grain, germinates / develops
growth of pollen tube (down the style) ;
pollen tube / A, enters, ovule / B

OR;; (male) nucleus / gamete fuses with, female gamete /
nucleus / egg cell (nucleus) / C ;
forms zygote ;
diploid

67
Q

3 adv of self-pollination for flowering plants

A

self-pollination perpetuates variety that is well adapted to habitat ;

greater chance of pollination

less wastage of pollen

68
Q

3 disadv of self-pollination for flowering plants

A

less, variation ;

less chance of adapting to changing conditions / AW ;

more susceptible to diseases

69
Q

dicots - mark scheme

A

network / AW, of veins / one (large) central vein ;

broad leaves ;

two, cotyledons / seed leaves ;

flower parts in multiples of, 4 / 5 ;
central / main, root ;
vascular bundles regularly arranged ;

Biology (N.A.) (21 decks)

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