SEXUAL REPRODUCTION? Flashcards

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1
Q

SCREEENSHOTTED

A

Variation in the
offspring

Natural selection
can be speeded up
by humans in
selective breeding

if the environment
changes variation
gives a survival
advantage by
natural selection
E.g. if there is a new
disease, there may
be some offspring
with resistance who
will survive

increase food
production for
humans

E.g. only allowing
cattle which
produce the most
milk to breed

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2
Q

male gamete?

A

The male gamete is called a sperm
and are produced in the male gonads
called the testes (singular= testis)

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3
Q

female gamete?

A

The female gamete is called an ovum
(plural = ova) (more commonly known
as an egg) and are produced in the
female gonads called the ovaries.

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4
Q

function of sperm?

A

The function of a sperm is to carry the male genetic
information and fertilise the female egg. The nucleus is haploid

(contains half the number of chromosomes as a body cell).

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5
Q

what does the flagellum tail do?

A

helps the sperm to swim

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6
Q

what does the tip of the head do?

A

contains enzymes to digest the coat of the egg

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7
Q

what gives the sperm a streamlined shape?

A

cytoplasm

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8
Q

function of egg?

A

The function of an egg (ovum) is to carry the female genetic
information and provide nutrients for the embryo following
fertilisation. The nucleus is haploid (contains half the number
of chromosomes as a body cell).

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9
Q

what does the cytoplasm have/do?

A

contains a store of food for energy

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10
Q

what does the jelly coat do?

A

it makes sure that only one sperm cell can enter the egg cell

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11
Q

what does the urethra do?

A

a tube which carries sperm through the penis during ejaculation. urine also passes the urethra to exit the body

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12
Q

what does erectile tissue do?

A

swells when filled with blood, to make the penis erect

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13
Q

what do the testes do?

A

where sperm is made

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14
Q

what do the glands do?

A

produce the liquid thats added to sperm to make semen

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15
Q

what do the vas defernes do?

A

(sperm duct) musclaur tube that carries sperm from testis towards the urethra

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16
Q

what does the scrotal sac do?

A

hangs behind the penis and contains the testes

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17
Q

what does the oviduct/fallopian tube do?

A

a muscular tube that carries the ovum from the ovary to the uterus

18
Q

what does the uterus/womb do?

A

the organ where an embryo grows

19
Q

what does the ovary do?

A

the organ that produces ova and sex hormones

20
Q

what does the cervix do?

A

the neck of the uterus

21
Q

what does the vagina do?

A

where the sperm are disposted

22
Q

sexual reproduction key facts?

A
  • offspring are gentically different to either parent
  • offspring inherit features from both parents
  • genetic info from 2 organisms is combined to produce offspring
  • the gametes fuse together to form a cell with a full number of chromosomes (fertilisation)
  • the mother and father produce gametes
  • in humans, each gamete contains 23 chromosomes-half the number of chromosomes in a normal cell
23
Q

why is variation in the offspring a advantage for sexual reproduction?

A

if the environment changes variation gives a survival

advantage by natural selection

24
Q

example for variation in the offspring?

A

E.g. if there is a new disease, there may be some offspring with resistance who will survive

25
Q

why is natural selection can be sped up by humans in selective breeding a advantage?

A

increase food prouduction for humans

26
Q

example for natural selection can be sped up by humans in selective breeding?

A

E.g. only allowing cattle which produce the most

milk to breed

27
Q

what is fertilaistaion?

A

The fusion of female and male gametes (haploid)

to form a new cell called a zygote (diploid).

28
Q

fertilisation explained?

A
  1. During sexual intercourse, sperm is ejaculated from the male penis into the female vagina.
  2. Sperm swims up the vagina and along the oviducts until it reaches the ovum (in the oviduct). Fertilisation occurs when one sperm fuses with one egg to form a zygote (fertilised egg).
  3. The zygote then undergoes cell division (mitosis) and develops into an embryo
  4. The embryo implants onto the lining of the uterus, and develops a placenta and an amniotic sac.
  5. When the embryo becomes recognisably human we call it a foetus.
29
Q

Time after Fertilisation: 30 hours

A

This is a zygote. It has only just been through fertilisation and has divided by mitosis
once.

30
Q

Time after Fertilisation: 1 week

A

The cells continue to divide by mitosis to form a ball of cells known as a blastocyst.

31
Q

Time after Fertilisation: 5 weeks

A

It is now the size of a raisin. The brain and spinal cord are starting to develop.

32
Q

Time after Fertilisation: 6 weeks

A

A heart has started to beat. Arms and legs start to form.

33
Q

Time after Fertilisation: 8 weeks

A

It is now called a foetus (Latin for young one). It is producing it’s own stomach digestive juices.

34
Q

Time after Fertilisation: 14 weeks

A

Muscles form and the baby starts to move. Eyelids,

fingernails, toenails form.

35
Q

Time after Fertilisation: 24 weeks

A

Fine hair and a waxy substance covers the body. It starts to ‘breathe’.

36
Q

Time after Fertilisation: 40 weeks

A

Welcome to the world. A normal baby is born

around this time.

37
Q

what is the placenta responsible for?

A

The placenta is responsible for providing oxygen and

nutrients, and removing waste substances.

38
Q

placenta details?

A

-It grows into the wall of the uterus and
is joined to the foetus by the umbilical
cord.

-The mother’s blood does not mix with
the foetus’s blood, but the placenta lets
substances pass between the two
blood supplies:

  1. oxygen and nutrients diffuse across the
    placenta from the mother to the foetus
  2. waste substances, such as carbon
    dioxide, diffuse across the placenta
    from the foetus to the mother.
39
Q

what is the foetus being protected by after birth?

A

The foetus is protected by the uterus and the amniotic

fluid, a liquid contained in a bag called the amnion.

40
Q

what is the amniotic sac?

A
  • Protects the baby
  • Sac that fills with fluid
  • Mostly foetal urine
  • For protection
41
Q

what is the umbilical cord?

A

connects the baby to the mother

42
Q

what is the placenta?

A
allows the
mother’s blood to come
close to the baby’s to allow
exchange of food, oxygen
and wastes