Biology Section 3: Reproduction and Inheritance (A (Reproduction…
Biology Section 3: Reproduction and Inheritance
types of reproduction
In sexual reproduction two parents create non-identical offspring, inheriting characteristics from both parents.
In asexual reproduction a single parent creates genetically identical offspring.
Gametes are sex cells:
the male one being sperm;
the female one being an egg
When they join together it is know as fertilisation. At this point the fused gametes become a zygote.
the zygot then divides repeatedly, at this stage it becomes an embryo.
Brightly coloured, larger petals
Anthers stick out- past other parts of the flower
Stamen will have large surface area.
A pollen will travel down the stigma through a pollen tube, in to the ovule in the carpel. Here the pollen will fertilise the ovule, forming a zygote (the seed). The carpel (reproductive organ) becomes a fruit.
conditions needed for germination
seed food reserves
Food reserves are in the cotyledons, sustain the plant growth until leaves are able to photosynthesis to support the plant.
Runners- eg strawberries- a second stem extend, when it reaches the ground cells specialise into root cells and a new plant develops.
Cuttings: a clipping is put in to plant hormones, encouraging the ends to become roots, when placed in soil it will then create another plant.
male reproductive system
Testis- produce sperm cells, they are stored in the epididymus
Vas deference- carries sperm to the penis
The prostate- adds fluid to the sperm, creating semen (as does the seminal vesicles)
The urethra- carries sperm to the end of, and out of the penis.
female reproductive system
Ovaries- produce eggs
Oviducts- carry the eggs to the uterus, is the site of fertilisation
Uterus- develops the fertilised egg on the placenta
Cervix- entrance to uterus
the menstrual cycle
Oestrogen: produced in the ovaries; thickens the womb lining; prompts the release of LH.
Progesterone: produced in the corpus lutiem; maintains the lining of the womb
Blood vessels inside the placenta can absorb the digested food molecules and oxygen that the embryo needs to survive.
The embryo can't breath, digest or excrete.
Waste products will be taken out of the embryo and put back into the mothers blood stream for her to excrete.
The fluid (mainly water) cannot be compressed- it absorbs pressure- so any force on the uterus wall will not harm the embryo.
Production of sperm
Growth of sexual organs
Body hair- pubic, arms and face
Body mass will increase, including muscle mass
Voice breaks (becomes deeper)
Development of a sexual drive
The beginning of the menstrual cycle
Body mass increases and redistributed- to hips and breasts
Body hair- pubic
Voice deepens slowly
Development of sexual organs