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Growth and Reproduction Flashcards

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1
Q

Describe the process of mitosis?

A
  1. The cell grows.
  2. The DNA replicates to form two copies of each chromosome. These chromatids are joined together at the centromere.
  3. The nuclear membrane breaks down. The chromosomes line up across the centre of the cell, attached to spindle fibres
  4. The chromatids are pulled apart and move to opposite ends of the cell.
  5. The cytoplasm and cell membrane divides forming two identical cells.
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2
Q

Describe the process of meiosis?

A
  1. The parent cell grows.
  2. The DNA replicates to form two copies of each chromosome. These chromatids are joined together at the centromere.
  3. The nuclear membrane breaks down. The homologous pairs of chromosomes join together.
  4. The homologous pairs of chromosomes exchange sections of DNA. They then attach to the spindle fibres in pairs.
  5. The homologous pairs of chromosomes are pulled apart and move to opposite ends of the cell. The cell divides.
  6. The chromosomes line up along the centre, attached to the spindle fibres. The chromatids separate and move to opposite ends of the cell. Each cell divides again.
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3
Q

Differences in the processes of mitosis and meiosis?

A

Mitosis:
*Produces genetically identical daughter cells
*Produces two cells
*Involves one division
*Produces diploid cells in humans
*Keeps the same chromosome number

Meiosis:
* Produces genetically non-identical
daughter cells
*Produces four cells
*Involves two cell divisions
*Produces haploid cells in humans
*Halves the number of chromosomes

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4
Q

Differences in the roles of mitosis and meiosis?

A

Mitosis:
*Generates all adult cells except gametes
*Occurs throughout the human body
*Occurs throughout a plant
*Used for asexual reproduction

Meiosis:
*Only used to produce gametes
*Only occurs in ovary and testis
*Only occurs in ovary and anther
*Used for sexual reproduction

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5
Q

What is external fertilisation?

A

In fish, the females release their ova into the water and the sperm have to swim through the water to fertilise the ova.

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6
Q

What is internal fertilisation?

A

Other male animals including birds and mammals, ejaculate their sperm in semen into the bodies of the females during sexual intercourse.

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7
Q

What are gametes?

A

Cells that half the genetic information required for fertilisation. (haploid cells)

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8
Q

What is a zygote?

A

The first cell that is formed at fertilisation

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9
Q

What is fertilisation?

A

Fertilisation is the fusion of haploid male and female gametes, restoring the diploid number of chromosomes in the zygote.

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10
Q

What are the parts of the female reproductive system?

A
  • ovary
  • oviduct
  • uterus (womb)
  • cervix
  • vagina
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11
Q

What are the ovaries?

A
  • where egg cells are formed by meiosis. Produces the hormones oestrogen and progesterone.
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12
Q

What is the oviduct?

A
  • egg cells travel down this to the uterus. Lined with cilia which move the cell.
  • site of fertilisation
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13
Q

What happens in the uterus/womb?

A
  • a lining forms in the uterus, where the embryo will implant.
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14
Q

What properties does the uterus/womb have?

A

The foetus develops in the uterus, which has a thick muscular wall. This contracts during labour.

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15
Q

What is the cervix?

A
  • narrow opening to the uterus. This dilates during labour, to allow the baby to be born.
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16
Q

What is the vagina?

A
  • muscular tube that leads from the cervix to the outside of the woman’s body.
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17
Q

What are the parts of the male reproductive system?

A
  • testes
  • sperm duct
  • seminal vesicle and prostate gland
  • penis
  • urethra
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18
Q

What are the testes?

A
  • where sperm cells are formed by meiosis. Produces the hormone
    testosterone.
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19
Q

What is the sperm duct?

A
  • maturing sperm are transported along this tube
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20
Q

What is the roles of the seminal vesicles and prostate gland?

A
  • release liquids into the sperm duct, which mixes with the sperm cells to form semen.
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21
Q

What is the role of the penis?

A
  • transports urine and semen out of the body
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22
Q

What is the urethra?

A
  • tube inside the penis which can transport either urine or semen.
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23
Q

What journey does sperm take during intercourse?

A

Sperm pass along the sperm duct, mixed with a fluid from the seminal vesicles. This semen, is ejaculated into the vagina out of the urethra. The sperm then swim towards the oviducts.

24
Q

How are sperm cells specialised?

A
  1. Has flagellum to allow sperm to swim
  2. Many mitochondria to provide energy needed for swimming
  3. Acrosome at the tip to digest the jelly layer surrounding the egg cell
25
Q

Why does fertilisation produce variation in offspring?

A
  • Each male ejaculate will contain millions of sperm cells. Each of these sperm cells is genetically different.
  • Each female egg cell will also be genetically different.
  • Which sperm cell fertilises the egg is random.
  • This ‘randomness’ causes variation in the genetics of the new offspring.
26
Q

What is the role of the placenta during the development of the embryo?

A
  • allows glucose and oxygen to diffuse from the mother’s blood to the embryo.
  • glucose and O2 allows respiration to occur.
  • amino acids from the mother’s blood allows proteins synthesis to occur.
  • transfer of fatty acids and glycerol so embryo can synthesise lipids.
  • removes CO2 and urea.
27
Q

How is the placenta connected to the embryo?

A

the umbilical cord.

28
Q

What is the role of amniotic fluid?

A

Protects the developing embryo against jolts and bumps, drying out, and temperature fluctuations

29
Q

Secondary sexual characteristics in males?

A
  • voice breaks
  • sperm production begins
  • shoulders broaden
  • facial, armpit and pubic hair grow
  • muscle development
  • growth of genitalia
  • mood swing + acne
30
Q

Secondary sexual characteristics in females?

A
  • voice deepens, but doesn’t break
  • the menstrual cycle begins
  • pelvis broadens in preparation for pregnancy and labour
  • armpit and pubic hair growth
  • muscle development + fat deposits on breasts, hips and thighs
  • growth and development of genitalia
  • mood swings and acne
31
Q

What is the role of FSH in the menstrual cycle?

A

Gland secreted from: pituitary
Target organ / Tissue: ovary follicle
Effect: follicle develops and ovum matures.

32
Q

What is the role of LH in the menstrual cycle?

A

Gland secreted from: pituitary
Target organ / Tissue: ovary follicle
Effect: ovulation - follicle on ovary releases matures ovum into oviduct, follicle becomes corpus luteum.

33
Q

What is the role of oestrogen in the menstrual cycle?

A

Gland secreted from: ovary (follicle)
Target organ / Tissue: pituitary
Effect: inhibits FSH production, stimulates LH production

34
Q

What is the role of progesterone in the menstrual cycle?

A

FSH and LH inhibited, thickness of uterine lining maintained.

35
Q

What hormones stimulates puberty?

A

LH and FSH

36
Q

What order are the hormones released in during the menstrual cycle?

A

FSH
Oestrogen
LH
Progesterone

37
Q

Compare sexual and asexual reproduction?

A
  • Gametes produced?
    yes in sexual, no in asexual.
  • Fertilisation?
    takes place in sexual doesn’t in asexual
  • Genetic variation?
    there is genetic variation in sexual but not in asexual.
  • Survival value?
    sexual has survival value asexual does not.
38
Q

Natural methods of asexual reproduction?

A
  • runners
  • tubers
  • bulbs
39
Q

How does asexual reproduction occur in runners?

A

A new plant is produced where the runner touches the ground.

40
Q

What are tubers and how does asexual reproduction occur in tubers?

A

Swollen underground stems containing lots of stored food.

One plant can produce many tubers which can each grow many shoots which form new plant.

41
Q

What are bulbs and how does asexual reproduction occur in bulbs?

A

Underground buds with thick fleshy leaves containing stored food.

A main shoot will grow out of the parent bulb and another will grow out of the side ‘daughter’ bulb, forming two plants.

42
Q

What are the artificial methods of asexual reproduction?

A
  • cuttings
  • grafting
43
Q

What is the method of cuttings?

A

A branch from the parent plant is cut off, its lower leaves are removed and the stem is planted in compost. Plant hormones are used.

44
Q

What is the method of grafting?

A

A cutting is attached on to the stem of another plant, the plants grow together.

45
Q

Advantages of sexual reproduction?

A
  • offspring are varied so have survival value.
46
Q

Advantages of asexual reproduction?

A
  • one parent needed
  • offspring are clones
47
Q

Where do the male gametes of the flower come from?

A

Pollen - is the gamete produced in the anther which is part of the male part (stamen) of the flower

48
Q

Where do the female gametes of the flower come from?

A

Ova - is the gamete produced in the ovules found in the ovary within the female park (carpel) of the flower

49
Q

What is cross-pollination?

A

The transfer of pollen from the anther of one flower to the stigma of another flower on another plant

50
Q

What is self-pollination?

A

When the pollen does not reach a different plant

51
Q

Differences between the features of insect pollinates and wind pollinated flowers?

A

Insect Pollinated:
- Stamen is enclosed within flower.
- Stigma is enclosed within flower and sticky
- Large and brightly coloured petals
- Nectaries are present and produce sugar fluid.

Wind Pollinated:
- Stamen is exposed
- Stigma is exposed outside of petals
- Petals small and dull in colour
- Nectaries are absent.

52
Q

Discuss the process of pollination of fertilisation in plants?

A
  1. Pollen grains deposited onto stigma.
  2. The pollen grain grows a pollen tube that grows down through the style.
  3. Enzymes secreted at the tip of the tube these digest the tissues of the style.
  4. When the tube reaches an ovule the male gamete travels through the tube entering the ovule through the micropyle.
  5. It then fuses with the ovum.
  6. The fertilised ovum divides by mitosis to form the embryo
  7. The ovule develops into the seed.
  8. The ovary develops into the fruit
53
Q

How is fruit formed?

A
  1. The zygote develops into an embryonic plant with a small root (radicle) and shoot (plumule)
  2. The other contents of the ovule develop into cotyledons which will be a food store for the plant when it germinates.
  3. The ovule wall becomes the seed coat, or testa.
  4. The ovary wall becomes the fruit coat.
54
Q

What conditions do seeds need to germinate?

A
  1. Oxygen - to aerobically respire
  2. Warmth - optimum temperature for enzymes
  3. Water - to activate the enzymes
55
Q

Describe and investigation to look at the conditions needed for germination?

A

Cress seeds are added to cotton wool in test tubes:
- Tube A is put in a fridge and the rest are kept on a windowsill.
- In tube C, the cotton wool is moistened with boiled water and an oxygen absorbed is added.
- Tube E is wrapped in foil.
- The cotton wool in tube B is kept dry.
- Tube D has all the conditions present.
Check for germination after 2-3 days

Biology (10 decks)

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