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Year 9 Biology > Human Reproduction > Flashcards

Human Reproduction Flashcards

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1
Q

How does meiosis work?

A

Meiosis involves two divisions.
Here’s how meiosis works:
Meiosis - Division 1
1) before the cell starts to divide, it duplicates its DNA (so there is enough for each new cell). One arm of each X-shaped chromosomes is an exact copy of the other arm.
2) in the first division in meiosis, the chromosomes line up in pairs in the centre of the cell. One chromosome in each pair came from the organism’s mother and one came from its father.
3) the pairs are then pulled apart, so each new cell only has one copy of each chromosome. Some of the father’s chromosomes and some of the mother’s chromosomes go into each new cell.
4) Each new cell will have a mixture of the mother’s and father’s chromosomes. Mixing up genes like this is really important - it creates genetic variation in the offspring.
Meiosis - Division 2
5) In the second division the chromosomes line up again in the centre of the cell. It’s a lot like mitosis. The arms of the chromosomes are pulled apart.
6) You get for haploid gametes. Each gamete only has a single set of chromosomes. The gametes are all genetically different.

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2
Q

By what method do human beings reproduce?

A

Sexual reproduction

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3
Q

What are the names of the male and female gametes in humans?

A

Sperm and egg cells

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4
Q

What do the gametes need to do for reproduction to be successful?

A

Fuse

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5
Q

What is the process called when the gametes fuse?

A

Fertilisation

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6
Q

What is the name of the cell produced when the gametes fuse?

A

A zygote

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7
Q

What does a zygote develop into?

A

An embryo

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8
Q

Draw and label diagrams of the male and female gametes

A

Include:
Ovum, jelly coat, cell membrane, nucleus, cytoplasm
Sperm cell, Tail for swimming, cell membrane, nucleus, cytoplasm

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9
Q

By which part of the reproductive system is the ovum made by?

A

The ovaries

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10
Q

By which part of the reproductive system are the sperm cells made by?

A

The testes

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11
Q

What are the differences between the male and female gametes?

A

Sperm cell:no food store, contains many mitochondria to release the energy needed for swimming
Ovum: large food store, fewer mitochondria as not much energy is needed

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12
Q

Draw and label a diagram of the female reproductive system

A

Include:
Site of fertilisation, oviduct, follicles, ovary, uterus lining, cervix, vagina, uterus (muscular wall)

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13
Q

Draw and label a diagram of the male reproductive system

A

Include:
Bladder, sperm duct, glands, urethra, penis, scrotum, testes

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14
Q

What are the different stages, in order, which the gametes go through before forming a baby

A
  • they fuse (fertilisation) forming a zygote
  • zygote develops into an embryo
  • embryo develops into a foetus
  • foetus develops into a baby
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15
Q

What are the functions of the different parts of the female reproductive system?

A

Oviduct- eggs are released into this tube and carried to the uterus. Fertilisation happens here.
Ovary- After puberty, and egg is released from here each month during ovulation
Uterus- Fertilised egg implants here, then develops into a foetus
Vagina- an elastic muscular tube leading to the uterus where sperm are deposited during sexual intercourse
Cervix- The entrance to the uterus from the vagina

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16
Q

What are the functions of the different parts of the male reproductive system?

A

Penis- becomes erect so that it can be placed into the vagina to transfer sperm into the female
Glands- produce a liquid called semen for the sperm to swim in
Urethra - the tube that carries both sperm and urine outside the body, although never at the same time
Testes- sperm are made here
Scrotum- holds the testes outside the body to ensure they are kept at a lower temperature than the body because at this temperature sperm production is inhibited
Sperm ducts- these tubes carry sperm from the testes to the penis

17
Q

When male humans are sexually aroused, their ……… fills with blood and becomes erect.
This enables the man to insert his ……… into his partners ………
Ejaculation takes place where about 5cm3 of liquid called ……… is forced out of the penis by rhythmic contractions of the sperm duct and other muscles.
The semen contains up to 100 million ……… This liquid contains chemicals which stimulate the swimming movements of the sperm.
Ejaculation deposits the semen at the top of the ………, near the cervix. From here, a few thousand sperms may manage to swim up to the ………, and if a ripe ……… is present at the same time, ……… may occur.
Only one sperm can fertilise the ovum. As this sperm penetrates the ovum, it instantly triggers the formation of an extra membrane around this cell, so that no other sperms can enter. Only the ……… of the sperm goes in; the tail is left outside.
Sperm cells can live for 2-3 days inside the female, and therefore intercourse two days before the egg is released from the ……… (………) can still result in fertilisation.

A

Penis, penis, vagina, semen, sperm, vagina, oviduct, egg/ovum, fertilisation, head/nucleus, ovary/ovulation

18
Q

What does the placenta in the amnion do?

A

The placenta brings the mothers blood supply very close to that of the foetus. This allows substances to be diffused between the mother and the foetus without any mixture of blood.

19
Q

Label a diagram of a human foetus developing in the uterus

A

Include:
The umbilical chord, the placenta, the muscular uterus wall, amniotic fluid, the amnion, the foetus

20
Q

Why do the mother’s and baby’s blood not mix in the uterus?

A
  • they may have different blood types (leading to blood clotting)
  • alcohol, drugs etc may be in the mother’s blood, harming the baby
  • the mother’s blood pressure would be too high and burst the developing foetus
21
Q

What are the substances transferred from the mother’s blood to the foetus’ blood?

A

Oxygen- for respiration to provide energy to grow
Glucose- for respiration
Amino acids- for growth
Vitamins + Minerals
Antibodies

22
Q

What are the substances transferred from the foetus’ blood to the mother’s blood?

A

Carbon dioxide- a toxic waster product of respiration
Urea- a toxic waste product of the breakdown of excess protein

23
Q

What are the adaptations of the placenta?

A
  • large surface area provided by finger-like projections called villi.
  • rich blood supply to supply what is needed and remove waste
  • steep concentration gradient for diffusion
  • very thin walls so there is only a short diffusion distance for substances to move
24
Q

What is the role of the amniotic fluid?

A
  • protects the baby from physical damage by cushioning it
  • controls variations in temperature
25
Q

How longs can the ovum wait for the sperm?

A

2 days

26
Q

How long can the sperm wait for the ovum?

A

5 days

27
Q

Describe the process of fertilisation

A
  • the sperm surround the egg
  • one sperm penetrates wall of the egg
  • the nucleus of the sperm moves toward the egg nucleus and, when they reach each other, they fuse together
  • a zygote has been formed
28
Q

Describe embryo development after fertilisation

A
  • the zygote travels to the uterus. This takes about 3 days during which it divides into a ball of 64 cells, which is now called an embryo
  • the embryo embeds in the thickened uterus lining and for the first three months gets its’ nutrients from the mother by diffusion from the uterus lining
  • the embryo continues to grow
  • at the end of the three months the placenta has developed and the embryo is now called a foetus as its’ organs can be identified
29
Q

Describe the pathway of the sperm cells

A
  • the sperm move through the sperm duct from the testes to the penis
  • the penis enters the vagina and releases the sperm
  • the sperm swim through the cervix and uterus
  • they ‘choose’ which oviduct to travel into, however only one oviduct has the egg cell
  • if the sperm has swam into the correct oviduct, it will try to break into the ovum wall and, if successful, it fuses with the egg cell (fertilisation occurs)
30
Q

What are secondary sexual characteristics

A
  • they develop under the control of hormones
  • they develop at puberty
  • some prepare the body for reproduction and others make it clear that the body is mature enough for reproduction
31
Q

What is the male hormone?

A

Testosterone

32
Q

Where is testosterone produced?

A

By the testes

33
Q

What is the female hormone

A

Oestrogen

34
Q

Where is oestrogen produced

A

In the ovaries

35
Q

What are the main secondary sexual characteristics in a male?

A
  • voice breaks
  • hair grows on face + body
  • body becomes more muscular
  • testes start to produce sperm cells
  • enlarged Adam’s apple
  • broader shoulders
36
Q

What are the main secondary sexual characteristics in a female?

A
  • voice deepens gradually
  • hips get wider
  • breasts develop
  • ovaries start to produce egg cells (menstruation starts)
  • pubic, leg and underarm hair grows

Year 9 Biology (5 decks)

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