41 - Human Reproduction

Draw a large diagram of the human male reproductive system

Give the names of tubes A and B and the name of gland C

A: Urethra

B: Sperm duct

C: Prostate

Give one function for each structure labelled A, B and C

A: Release semen or release urine

B: Carries sperm from testes to urethra

C: Produces seminal fluid

Give the function of the epididymis

To store sperm or to allow sperm to mature

In which part of the male reproductive system does meiosis occur?

Testes

Explain the importance of meiosis in the production of sperm

To produce haploid cells or to maintain parental chromosome number or introduce variation

Name the male sex hormone produced by the testes

Testosterone

Which part of the male reproductive system is directly involved in copulation?

Penis

How many chromosomes are found in the nucleus of a typical human sperm cell?

23

Indicate the location of the mitochondria on this diagram of the human sperm cell

Suggest why a sperm cell needs to many mitochondria

They need a lot of energy or need to swim long distances

Mitochondria are inherited exclusively from the mother. Suggest why this is the case

Only the head of the sperm enters the egg

no sperm mitochondria enter the egg

State the approximate survival times of the egg and sperm within the female reproductive tract

Egg: 12 - 48 hours

Sperm: 0 - 7 days

What is meant by the term inferitility?

Inability to produce offspring

Give one cause of male infertility and a corrective measure

Cause: low sperm count / low sperm mobility

Corrective measure: IVF

Give any two methods of contraception

Mechanical / surgical / natural / chemical / named examples

Give one named example of natural contraception

Abstinence or rhythm

Draw a labelled diagram of the human female reproductive system

Where do the following occur in the female reproductive system:

1. Egg production

2. Fertilisation

3. Implantation

1. Ovary

2. Fallopian tube

3. Uterus

How long is the typical menstrual cycle in a human female?

28 - 31 days

What is the role of the menstrual cycle?

To prepare uterus for pregnancy

What is meant by the term menstruation?

Breaking down of the endometrium

Name each of the hormone A and B

A: Oestrogen

B: Progesterone

Describe one effect on the female reproductive system of the low levels of hormones A and B

Menstruation or FSH produced or new follicle starts developing

Explain why hormone A levels increase after approximately day 5

Follicle secretes more oestrogen or FSH stimulates production of oestrogen

FSH and LH each play a role in the cycle. Where in the body are these hormones produced?

Pituitary gland

Give the functions of the other two named hormones involved in the cycle

Oestrogen: causes endometrium to build up or inhibits FSH or stimulates LH

Progesterone: maintains endometrium or inhibits LH or inhibits FSH

What event occurs around day 14 of the menstrual cycle?

Ovulation or release of egg (from the ovary)

Explain why hormone B levels increase in the days after day 14

Corpus luteum secretes progesterone or LH stimulates production of progesterone

The graafian follicle increases in size during the first half of the menstrual cycle.

Name the main hormone the graafian follicle produces

Oestrogen

Name the structure that the graafian follicle develops into after day 14

Corpus luteum

Give the function of the hormone you named in the previous question

Repair of the endometrium

What hormone is responsible for causing ovulation?

Luteinising hormone (or LH)

What name is given to structure A?

Corpus luteum

Name the main hormone that is produced by structure A

Progesterone

Describe what happens to structure A if fertilisation of an egg cell does not occur

It degenerates (towards the end of the menstrual cycle)

Does the graph indicate that the woman became pregnant during this menstrual cycle? Explain your answer

No

Explain: uterine lining breaks down at the end or corpus luteum breaks down

Name a menstrual disorder and state a cause and a possible treatment

Name: Fibroids

Cause: Hormonal imbalance

Possible treatment: Hormonal medication

What is meant by the term secondary sexual characteristics?

Features that distinguish male from female other than sex organs or features that emerge at puberty

Give two examples of a secondary sexual characteristic present in males

Deep voice / enlarged muscles / wide shoulders / body hair / enlargement of penis

Give the names of two structures that are formed in the days following fertilisation up to the point of implantation

Morula

Blastocyst

True or false

The morula forms before the blastocyst in human reproduction

True

Name the next stage of development following formation of the zygote in humans

Morula

What is meant by the term implantation?

Embedding of the fertilised egg into the endometrium

Outline what happens to each of the following after implantation has taken place:

1. The level of the hormone progesterone in the blood

2. The endometrium

1. Progesterone level: Increases

2. Endometrium: Is maintained or thickens

Embryo cells organise into three germ layers.

Name each of these layers

Ectoderm

Mesoderm

Endoderm

Identify the germ layer from which the skin of the developing embryo arises

Ectoderm

From which tissues does the placenta form?

Endometrium

Chorionic

Describe the differences between the human male and female type of gamete using the following headings:

1. Relative numbers of each produced

2. Frequency of production of gametes

3. Relative size

1. A low number of female gametes and a high number of male gametes

2. Monthly in females and continuously in males

3. Large in females and small in males

Name the two tissues involved in the formation of the placenta

Tissue 1: Endometrium or uterine

Tissue 2: Embryonic or embryo tissue

Give two roles of the placenta

Movement of food or waste from mother to foetus / endocrine gland or production of hormones

Give two reasons why the blood of the mother and the foetus must not mix

Blood pressure difference / Blood group difference / to prevent transfer of certain infections

Give an outline description of the birth process, including the role of hormones

Placenta stops producing progesterone

Pituitary gland of the mother produces oxytocin

Mucus plug falls out / amniotic fluid expelled / labour of uterine contractions / cervix dilates / baby is pushed out / afterbirth / umbilical cord is cut

State one method of birth control

Condom or the (contraceptive) pill or IUD

Name the hormone responsible for milk production

Prolactin

State two biological benefits of breastfeeding

Balanced supply of nutrients / supplies antibodies / correct temperature

Give an advantage and a disadvantage of sexual reproduction in organisms

Advantage: Increased variation

Disadvantage: Requires two parents or longer life cycle

Explain the term in vitro fertilisation

Gametes fuse

Outside the body

Suggest a reason for the removal of several eggs

To increase chance of successful implantation