Reproduction Flashcards
What are the characteristics of asexual reproduction in plants?
- No gametes
- No fertilisation
- No variation in offspring
- Good survival in a stable environment
What are the characteristics of sexual reproduction?
- Gametes produced in meiosis
- Fertilisation
- Variation in offspring
- Survival value in changing environment
What changes do the sex called in plants undergo?
Male gamete + female gamete (fusion)
→zygote -cell division→ embryo
What is the make gamete in plants?
Pollen produced in the anthers
What is the female gamete in plants?
Ova produced in the ovules
Define pollination
The transfer of pollen from the anthers of a plant to the flower
What are the characteristics of an insect pollinated flower?
- Anther and stamen inside the flower
- Sticky stigma inside flower
- Large, sticky pollen grains
- Large, bright petals
- Nectary
What are the characteristics of a wind pollinated flower?
- Anther and stamen outside the flower
- Feathery stigma outside
- Small and light pollen grains
- Small, usually green petals
- No nectary
What are the stages of fertilisation?
- Pollen transferred to stigma
- Pollen tube grows down the style
- Into ovary
- Into ovule
- Male nucleus fuses with female nucleus
How are seeds and fruit formed?
- Ovule develops into a seed
2. Ovary develops into fruit
What are the conditions for germination?
Why?
- Warm - germination improves as temperature rises (up to a point)
- Moist - allows the seed to swell up which allows the embryo to start growing
- Oxygen - energy can be released for germination
What are the squiggly tubes running alongside the testes?
The epididymis
What is the tube that runs from the epididymis to the urethra?
The vas deferens - stores sperm
What’s the flowery thing at the start of the urethra?
The prostate gland - produces semen
What is the tube running from the kidney to the bladder?
The ureter - carries urine to the bladder
What do the testes do?
Form sperm by meiotic cell division. Only occurs below body temperature
What is the entrance to the uterus called?
The cervix
What happens in the ovaries?
Egg and hormone production
What is the tube running from the egg to the uterus called?
The oviduct
Where does fertilisation occur?
In the Fallopian tubes
What happens in fertilisation?
- The head of a sperm enters the egg an the nuclei fuse to form a Zygote
- If two eggs are released, twins may occur
- Identical twins happen if the egg splits in half after fertilisation
What are the male gametes in humans?
The sperm
What are the female gametes in humans?
The ova
How often is an egg produced?
28 days
What does oestrogen cause in women?
- Pubic hair
- Widening hips
- Breast development
- Ovum release and periods start
What does testosterone cause in men?
- Extra hair on face and body
- Muscle development
- Penis and testicles enlarge
- Sperm production
- Deepening of voice
What happens during the menstrual cycle?
- Uterus lining breaks down for about 4 days
- Uterus lining builds up 10 days
- Ovum develops and is released
- Wall is maintained for about 14 days
In menstruation, what does oestrogen do?
- Causes uterus lining to thicken and grow
2. Stimulates the ovum release
What does progesterone do in menstruation?
Maintains the thickness of the uterus lining
When fertilised, what does an egg develop into?
An embryo
What happens once the embryo is implanted?
The placenta develops and the baby develops into a fetus
What is the role of the placenta?
Nutrients and oxygen are diffused through it to the baby
How is the placenta adapted to do its job?
It has villi
