3a) Reproduction

Sexual Reproduction Vs. Asexual Reproduction:

Sexual	Asexual
gametes- sex organs	no gametes
not easily wiped out by disease- resistant	easily wiped out by disease- genes the same
fertilisation	no fertilisation
variation	no variation- clones
Meiosis	Mitosis

Flowering Plants 

Carpel- Female parts:

• Stigma (sticky)- pollen sticks to it 
• style- rod-like section that supports the stigma
• ovule
• ovary- contains female gametes (eggs) 

Stamen- Male parts:

• Anther- contains pollen grains- produce male gametes 
• Filament- stalk that supports anther

Sepal is the small green leafy part that protects the flower bud. 

Insect- pollinated Vs. Wind-pollinated 

	Insect	Wind
Petals	large and brightly coloured to attract insects	small and not brightly coloured
Nectary	To attract insects	absent
Scent	sweet to attract insects	absent
Stigma	enclosed within the flower so that insects must make contact	exposed to catch pollen in the wind
Stamen	quite a lot of anther on the top	exposed and anthers around the filament

Fertilisation- Steps:

1. Pollination takes place when pollen goes on the stigma 
2. Pollen germinates if the grain matches chemicals in stigma (triggered by) 
3. Pollen tubes begin to form and enzymes digests through the style to reach ovary 
4. nucleus of male travels down tube to female nucleus in ovule 
5. Nucleus' fuses together so there is fertilisation and the zygotes form

Different types of seed disperal:

• Mechanical 
• Animal 
• Exploding 
• Wind 
• Tide 

Seed germination:

Conditions

- Water: to activate the enzymes that break down the food reserves in the seed

- Oxygen: for aerobic respiration 

- Warmth/Temperature: For the enzymes inside the seed to work

Steps:

The radicle grows before the plumule as it needs to get water and nutrients- sugars, at the moment comes from the food store (cotyledon) 

Methods of asexual reproduction:
 Natural; budding, bulbs, regeneration
Artifical: cuttings, tissue culture, cloning

Humans 

Parts of the Male Reproductive system:

*testis: where the sperm is kept and produced 

*epididymis: sperm development 

*seminal vesicle: fluid containing fructose enzymes and protein for energy in sperm 

*urethra: carries urine from the bladder and sperm 

*ureter: from kidney to ureter to bladder to urethra 

*scrotal sac: hangs behind the penis and contains the testes

*sperm duct: muscular tube that carries sperm from testis towards the urethra 

Parts of the Female Reproductive system: 

*fallopian tube/oviduct: takes released eggs from the ovary 

*cervix: ring of muscle between the uterus and vagina and keeps baby in place during pregnancy 

*ovary: contains ovum (eggs) 

*uterus(womb): muscular sac and site of fertilisation of egg

*vagina; stretches to allow baby and opening for male penis 

Menstrual Cycle:

Stage One Day 1- when bleeding starts and the lining of uterus breaks down 

Stage Two Day 4 to 14- the uterus builds up again, ready to receive an egg

Stage Three Day 14- Ovum develops and is released, this is called ovulation 

Stage Four Day 14-28- Wall is maintained 

Role of oestrogen and progesterone in the menstrual cycle:

Oestrogen ---> Causes the lining of the uterus to thicken and grow and stimulates the release of an ovum at day 14
Progesterone ---> Maintains the lining of the uterus. When the level of progesterone falls, the lining breaks down

Role of LH and FSH in the menstrual cycle:
FSH ---> stimulates the ovary to get the egg ready for release and secrete oestrogen
LH ---> triggers ovulation after being released by oestrogen

Placenta:
The organ of the uterus of pregnant mammals which allows the transfer of nutrients (water, glucose and oxygen) and waste products (urea, carbon dioxide) between mother and foetus through umbilical cord.

Amniotic Fluid:
Surrounds and protects the developing embryo in a sac protects from bones etc. Protects the embryo against knocks and bumps.

Secondary Sexual Characteristics:
Oestrogen in women causes
*Extra hair on underarms and pubic area
*Hips widen
*The development of breasts 
*Ovum release and start of periods 

Testosterone in women causes
*Extra hair on face and body
*Muscles develop
*Penis and testicles to enlarge 
*Sperm production
*Voice deepens