sexual reproduction in humans 2025 year 2 flash cards

What is Sexual reproduction?

it is the fusion of male and female gametes to form a zygote.

What are gametes?

Gametes are specialised reproductive cells (male-sperm, female-ovum)

Why are sexually reproduced off spring genetically different from either parent?

The offspring inherit a unique combination of genes from both the mother via the ovum and the father via the sperm. This results in variation between individuals.

What is asexual reproduction?

Reproduction without fusion of gametes.

Why are offspring produced by asexual reproduction genetically identical to the parent?

No genetic variation is introduced as there is only one parent.

Why is sexual reproduction more advantageous in a changing environment?

Genetic variation increases the chances of individuals being better adapted, supporting survival and evolution

Why is asexual reproduction more advantageous in a stable environment?

1. Off spring are identical to the parents so they are already suited to the environment

2. Faster reproduction helps the species populate the habitat quickly.

What is the male gonad, gamete and sex hormone respectively?

Testes, Sperm, Testosterone

What are the female gonads, gametes and sex hormones respectively?

Ovary, ova/ovum, Oestrogen AND progesterone

What’s the function of the testis?

To produce sperms and testosterone

What is the function of the epididymis?

To store sperm and allow sperm to mature

What is the function of the scrotums?

To hold testes outside the body to maintain a lower temperature for optimum sperm development.

What is the function of the prostate gland, seminal vesicles and Cowper’s gland?

They produce seminal fluid, which is nutrient-rich and slightly alkaline(pH 7.2-8.0). → Seminal fluid mixes with sperm to form semen to support semen survival and provides a medium for super movement

Sperm duct function?

The sperm duct transports sperm from testes to urethra during ejaculation by peristalsis

Urethra function?

Transports sperm or urine out of the body

Penis function?

Penis is an erectile organ that deposits semen into vagina during sexual intercourse.

Function of ovary?

1. Produces ova, oestrogen and progesterone

2. Releases one mature ovum during each menstrual cycle (per ovary)

Function of Uterus?

1. Is a hollow organ where foetus develops.

2. Embryo implants in the endometrium (uterine lining) at the bottom of the uterus.

3. The smooth walls of the uterus contracts during child birth

Function of oviduct?

1. Transports immobile ovum to uterus via cilia sweeping action and peristalsis of oviduct walls

Function of cervix?

1. Is the narrow neck at the base of the uterus

2. Dilates during childbirth for baby to pass through

Vagina function?

1. Receives sperm during sexual intercourse

2. Passage for blood and uterine tissue to leave during menstruation

Vulva function?

Vulva is the opening to the vagina

What is the main function of the menstrual cycle?

To prepare the endometrium (uterine lining) for the implantation of an embryo

What hormones are involved in menstrual cycle?

Oestrogen and progesterone and luteinising

What’s the average cycle length of menstrual cycle and what can affect it?

28 days (can vary between 21-35 days)

Is affected by STRESS, ILLNESS, DIET, MALNUTRITION and is PAUSED during PREGNANCY

What happens during first 5 days of menstrual cycle?

1. Low levels of oestrogen and progesterone causes uterine lining to break down

2. Menstruation occurs ( blood and uterine lining are discharged through the vagina)

What happens during day 6-14 of the menstrual cycle?

1. Follicle stimulating hormones stimulates follicles in ovaries to secrete oestrogen, causing thickening of uterine lining

2. Luteinising hormone triggers OVULATION

When is ovulation day for most women?

Day 14

What happens during day 15-day 28 of the menstrual cycle?(Right after ovulation)

High levels or progesterone maintain the uterine lining.

When is the fertile phase during the menstrual cycle and how to calculate it?

Day 10-15

last day of menstrual cycle-18(day 10) last day of menstrual cycle-13(day 15)

What is the journey to the oviduct of the sperm for fertilisation?

Vagina-cervix-uterus-oviduct

What is the placenta formed from? E_ V_ and U_ L_

Embryonic villi and uterine lining

What is the amniotic sac?

Amniotic sac is a membrane that encloses the embryo and foetus in the amniotic cavity

Function of amniotic cavity? (got 4)

Amniotic cavity contacts amniotic fluid that:

1. Allows free movement of foetus

2. Protects foetus from physical shocks

3. Maintains stable environment for foetus

4. Lubricates vagina during childbirth

What is the placenta?

A temporary organ formed from both the embryo and the mother’s tissue

Why no direct mixing of maternal and foetal blood? (3 reasons)

1. Higher bloody pressure of mother may damage foetal capillaries

2. Possible blood group incompatibility could cause blood clot

3. Some harmful substances may be blocked from entering foetal blood

How to calculate fertilisation day

Last day-14

How to calculate day of implantation?

Last day-14-5 TO last day-13-7

What is the function of the placenta?(3)

1. Secrets oestrogen and progesterone to maintain healthy pregnancy

2. Facilitates exchange of substances between mother and foetus via diffusion and active transport but no direct mixing of maternal and foetal blood