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IGCSE Biology > III: 1 - Reproduction (part 2) > Flashcards

III: 1 - Reproduction (part 2) Flashcards

1.2.2 Sexual reproduction in humans 1.3 Sex hormones 1.4 Methods of birth control 1.5 Sexually transmissible diseases

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1
Q

Locate and state the function of:

the ovaries

A

on diagram: Y

The ovaries form, store, mature and release egg cells. They also produce oestrogen.

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2
Q

Locate and state the function of:

the oviducts

A

on diagram: X

The oviducts or Fallopian tubes carry the egg cell/ovum from the ovary to the uterus. They are lined with cilia that help to push/waft the egg cell along (as the egg cell itself is immoblie).

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3
Q

Locate and state the function of:

the uterus & the endometrium

A

on diagram: W

The uterus is the cavity within which the fetus develops. The endometrium is the uterus lining in which the embryo implants itself.

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4
Q

Locate and state the function of:

the cervix

A

on diagram: P

The cervix is a ring of muscle that controls the uterus opening where it joins the vagina.

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5
Q

Locate and state the function of:

the vagina

A

on diagram: R

The vagina is the canal in which sperms are deposited, and is also the birth canal.

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6
Q

Locate and state the function of:

the clitoris

A

on diagram: T

The clitoris is a sensory spot.

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7
Q

Locate and state the function of:

the labia

A

on diagram: S

The labia is a flap that cover the female openings for protection.

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8
Q

State the name of these parts on the diagram:

  • AA
  • U
  • Q
  • O
A
  • AA: urethra
  • U: front of pelvic girdle
  • Q: anus
  • O: rectum
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9
Q

Locate and state the function of:

the testes

A

on diagram: I

The testes produces and stores sperm, and produces testosterone.

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10
Q

Locate and state the function of:

the scrotum

A

on diagram: H

The scrotum is a sac that protects a testis.

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11
Q

Locate and state the function of:

the epididymis

A

on diagram: J

The epididymis is a coiled structure that stores and matures sperms in males. All the sperm-producing tubes in the testis join to form ducts leading to the epididymis.

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12
Q

Locate and state the function of:

the sperm ducts (vas deferens)

A

on diagram: K

Two muscular tubes, each connected to a testis. They carry the sperms from the testis to the urethra.

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13
Q

Locate and state the function of:

the seminal vesicle

A

on diagram: B

Like the prostate gland, it secretes nutritive fluids for sperms to feed from and swim in, forming semen

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14
Q

Locate and state the function of:

the prostrate

A

on diagram: M

Like the seminal vesicle, it secretes a nutritive fluid to the sperms to form a mixture called semen

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15
Q

Locate and state the function of:

the penis

A

on diagram: F

The male sex organ which ejaculates semen into the vagina during sexual intercourse

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16
Q

Compare human male and female gametes in terms of size, numbers, mobility and sex chromosomes

A

Sperm:

  • very small (about 0.01 mm)
  • approximately 5 million are released at once
  • can move fast due to having a tail/flagella as well as being streamlined
  • sex chromosomes can be X or Y

Egg cell:

  • larger than sperm, about 0.1 mm
  • usually only one released at a time
  • cannot move on its own; is moved along by cilia in oviduct
  • sex chromosomes are always X
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17
Q

What four hormones affect the menstrual cycle?

A
  • Oestrogen
  • Progesterone
  • Follicle-stimulating hormone (FSH)
  • Luteinising hormone (LH)
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18
Q

What is the role of FSH (follicle stimulating hormone) in females?

A
  • secreted by the pituitary gland
  • causes an egg to mature in an ovary
  • stimulates the ovaries to release the hormone oestrogen
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19
Q

What is the role of oestrogen in females?

A
  • Produced in the ovaries
  • Gives females their secondary sexual characteristics
  • Stimulates the repair and build up of the endometrium
  • Prepares the uterus for implantation
  • Stimulates the release of LH
  • Inhibits the release of FSH, so only one ovum matures in a cycle
  • Causes change in the cervical mucus
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20
Q

What is the role of LH (luteinising hormone) in females?

A
  • produced in the pituitary gland
  • signals the ovary to release a mature egg from the Graafian follicle
21
Q

What is the role of progesterone in females?

A
  • produced by the corpus luteum after ovulation
  • helps to maintain the uterus lining
  • during pregnancy, progesterone is produced by the placenta
22
Q

Describe days 1 to 15 of the menstrual cycle in terms of the changes in the ovaries and uterus.

A

Day 1 to 5:

  • In the ovary, FSH secreted by the pituitary gland to stimulate the maturation of one follicle in the ovary.
  • In the uterus: the endometrium breaks down; this is called menstruation

Day 5 to 12:

  • The follicle keeps maturing in the ovary
  • In the uterus, oestrogen is secreted by the follicle and the ovarian tissues to prepare the endometrium for implantation

Day 13/14/15:

  • In the ovary, LH secreted by the pituitary gland to triggers the release of the egg from the Graffian follicle into the fallopian tube
23
Q

Describe days 15 to 28 of the menstrual cycle in terms of the changes in the ovaries and uterus.

A

Day 15 to 28:

  • In the ovary, LH triggers the formation of the corpus luteum
  • In the uterus: progesterone is secreted by corpus luteum to keep the endometrium thick, waiting for possible embryo implant.

Day 28 – Scenario 1: Egg not fertilized

  • No implantation takes place; the corpus luteum degenerates, causing a lack of progesterone.
  • This causes the endometrium to break down - menstruation again, back to day 1

Day 28 – Scenario 2: Egg is fertilized

  • Implantation occurs.
  • This makes the hormones to keep the corpus luteum maintained, meaning progesterone is kept high.
  • This keeps the endometrium thick for pregnancy.
24
Q

How is the egg cell transported from the ovary to the uterus after ovulation?

A

The movement of the cilia in the oviducts push the egg cell along to the uterus.

25
Q

Describe fertilisation (in humans)

A

Fertilisation is when the nucleus of a sperm cell fuses with the nucleus of the ovum/egg cell to form a zygote with a diploid nucleus.

  • One sperm penetrates
  • The ovum membrane alters to form a barrier against other sperm
  • Head of sperm (male nucleus) approaches and then fuses with the nucleus of the ovum.

This happens in the fallopian tube/oviduct of the female.

26
Q

Outline the early development of the zygote and the development of the fetus

A
  • Zygote divides over and over, to make a ball of cells called an embryo.
  • Implantation occurs when the embryo buries itself in the uterus wall (endometrium)
  • The embryo produces the placenta, which attaches to the endometrium with finger-like projections
  • The embryo is attached to the placenta by the umbilical cord
  • The embryo is changed through growth (mitosis) and development (organization of cells into tissues and organs)
  • After 11 weeks the embryo is considered a fetus
27
Q

What are the functions of the amniotic sac and fluid?

A
  • protects fetus against infection
  • prevents drying out
  • prevents mechanical injury by cushioning the fetus against impact
  • keeps temperature constant
  • keeps fetus buoyant
28
Q

What are the functions of the placenta?

A
  • produces progesterone to maintain thickness of endometrium
  • allows substances to diffuse from the blood of the fetus to the mother and vice versa
29
Q

What are the chorionic villi?

A

The chorionic villi are finger-like projections grown into the uterus wall from the placenta in order to give maximum surface area for diffusion.

30
Q

What is the function of the umbilical artery?

A

The umbilical artery carries blood away from the fetus to the placenta, containing waste materials such as carbon dioxide, and nitrogenous wastes like urea.

31
Q

What is the function of the umbilical vein?

A

The umbilical vein carries blood towards the fetus from the placenta containing nutrients such as glucose, amino acids, fatty acids and glycerol, antibodies, hormones and oxygen. It may also carry unhealthy substances such as drugs and alcohol, if the mother takes them.

32
Q

Why must the blood of the mother and fetus never mix?

A

The mother and fetus may have different blood types, and their mixing would be fatal to both of them as it will result in clotting.

33
Q

How do subtances from the mother’s blood reach the fetus’s blood (and vice versa)?

A

Subtances will diffuse across from the mother’s blood to the fetus’ blood (and vice versa) within the placenta.

34
Q

Describe the ante-natal care of pregnant women

A
  • Change in diet:
    • More proteins → growth of fetus
    • Slightly more fat → the new cells’ cell membrane
    • More vitamin C and D → blood vessel walls and bones
    • Iron → haemoglobin
    • Calcium → growth of bones and teeth
    • Folic acid → development of spine
  • Guidance on motherhood
  • Checks on fetus and mother including: weight check, blood tests, urine tests, blood pressure checks, ultrasound scanning etc.
  • Generally maintaining good health
35
Q

Why must a pregnant women eat more green, leafy vegetables?

A

Green, leafy vegetables contain folic acid, which is important for the development of the fetus’s spine. A deficiency in folic acid can result in spina bofida.

36
Q

What are the 5 main events of labour (parturition)?

A
  1. Uterine wall contracts and pushes fetus
  2. Cervix widens
  3. Amnion breaks and fluid escapes
  4. Head of fetus emerges
  5. Umbilical cord is cut
  6. Afterbirth - placenta is pushed out
37
Q

What is the difference between fraternal and identical twins?

A

Fraternal twins are formed from two different ova and are non-identical.

Identical twins are formed when a single zygote splits into two and forms two embryos with the same genetic material.

38
Q

What are the advantages of breast feeding?

A
  • milk contains high level of nutrients
  • milk is easily digested
  • milk contains antibodies
  • contents of milk vary to meet the changing nutritional requirements of the baby
  • milk is always at the correct temperature
  • no preparation time
  • free
  • decreases baby’s risk of obesity and SIDS
  • bonding time between mother and baby
39
Q

What are the disadvantages of breast feeding?

A
  • mother must be available
  • may cause pain or discomfort to mother
  • harmful substances from mother get passed on to baby
  • no way of telling how much baby is consuming
40
Q

What are the advantages of bottle feeding?

A
  • anyone can feed the baby
  • prevents transmission of disease from mother
  • can measure how much baby is drinking
41
Q

What are the disadvantages of bottle feeding?

A
  • preparation time for formula milk
  • expensive
  • baby may not tolerate formula
  • must carry equipment for bottle feeding
42
Q

Describe the role of testosterone in the development and regulation of secondary sexual characteristics at puberty

A

The testes start to produce sperm and release testosterone into the bloodstream, giving males their secondary sexual characteristics:

  • Enlargement of testes and penis
  • Voice deepens
  • Hair: pubic region, armpits, chest, face
43
Q

Describe the role of oestrogen in the development and regulation of secondary sexual characteristics at puberty

A

At about the same time as the first ovulation, the ovaries begin to release oestrogen into the bloodstream, giving females their secondary sexual characteristics:

  • Enlarged breasts
  • Widened hips
  • Pubic hair
  • Menstruation starts
44
Q

What different methods of birth control are there?

A
  • natural (abstinence, rhythm method)
  • chemical (contraceptive pill, spermicide)
  • mechanical (condom, diaphragm, femidom, IUD)
  • surgical (vasectomy, tubectomy)
45
Q

Describe artificial insemination (AI), and list its social implications

A
  • Male infertility - caused by low sperm count of sperms which are insufficiently mobile
  • Sperm donor - another man who donates his sperm to fertilise the women’s eggs
  • Semen is injected through a tube into the top of the uterus
  • Religious/moral objections
  • Child may never know biological father
  • Legal problems about the legitimacy of the child in some countries
46
Q

Describe in vitro fertilisation (IVF) and list its social implications

A
  • the woman is first given fertility drugs (containing FSH and LH) to make her produce a lot of eggs
  • eggs are then taken out of the woman and replaced in a sterile dish, and the man’s sperms added
  • a fertilised egg is chosen and put back in the woman’s uterus
  • unwanted embryos are destroyed
  • couples can choose embryos with ‘desirable’ qualities and destroy the rest
  • religious objections
47
Q

Describe the use of fertility drugs and list the social implications

A
  • drugs contain FSH to stimulate eggs to mature and LH to stimulate ovulation
  • administration of the drug is timed to promote ovulation to coincide with copulation
  • may result in multiple conceptions
  • too many devloping fetuses may stunt growth
48
Q

Gonorrhoea:

Signs & Symptoms: ?

Effects: ?

Treatment: ?

Prevention: ?

A

Signs & Symptoms: (males) Yellow, pus filled discharge from the urethra, burning sensation during urination, painful and swollen testes. (females) Vaginal discharge but no pain.

Effects: Bacteria reproduction in the urethra (males) or cervix (females). First signs occur within 5-7 days. If left untreated, the disease can travel through reproductive tract, causing sterility.

Treatment: antibiotics

Prevention: Abstain from sexual intercourse, have only one sexual partner, use condom, trace, warn and treat sexual partners with the disease to stop it from spreading.

49
Q

HIV (human immunodeficiency virus)

Transmission: ?

Effect on immune system: ?

A

Transmission: direct contact of body fluids, sexual intercourse

Effect on immune system: attacks lymphocytes, weakening the immune system

  • virus infects lymphocytes (white blood cells)
  • attacks T-cells and uses them to make copies of itself
  • destroys T-cells so immune system is not strong/nonfunctional
  • virus mutates to mask itself
  • about 10 years later, the patient develops AIDS

IGCSE Biology (24 decks)

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