Castlehead High School Factors affecting variety in a species – Reproduction in Mammals and Plants Intermediate 2 Environmental Biology & Genetics
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Castlehead High School
Factors affecting variety in a species – Reproduction in Mammals and Plants
Intermediate 2
Environmental Biology & Genetics
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Sexual Reproduction
• A species is when two organisms are able to interbreed and produce fertile offspring
• Sexual reproduction is the production of new members of a species using sex cells ( gametes )
• Fertilisation is the fusion of two gametes to form a new organism
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Male Reproductive System
PenisTestes
Sperm duct
UrethraGametes in male mammals are sperm -produced in the testes
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Female Reproductive System
Uterus
Vagina
Oviduct
OvaryCervix
Gametes in female mammals are eggs - produced in the ovaries
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Fertilisation in mammals
• The release of an egg from the ovaries is called ovulation
• Following sexual intercourse sperm swim towards the egg as it is wafted along the oviduct
• If a sperm meets the egg in the oviduct fertilisation occurs, the nucleus of the sperm and egg fuse and a zygote is formed
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Fertilisation in mammals
• During fertilisation one set of chromosomes from the sperm fuses with another set from the egg to form a zygote with 2 sets of 23 chromosomes - 46 in total
• Sexual reproduction gives the opportunity for genetic material from two different individuals to meet
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Gamete production in flowering plants
Gametes in a flowering plant are:
• Male – pollen, formed in anthers
• Female – ovules, formed in ovaries
Stigma
Style
Ovary
Anther
Ovule
Petal
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Fertilisation – Pollinationthe transfer of pollen from anther to stigma
A pollen grain lands on the STIGMA.
A POLLEN TUBE grows down the STYLE towards the OVARY.
The MALE NUCLEUS travels down the pollen tube.
Where it joins with the OVUM NUCLEUS in the OVARY.
This is called FERTILISATION. From this fertilised ovum called a ZYGOTE a SEED will grow.
Pollen
Stigma
Pollen tube
Style
Ovary
Ovum
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More to do
• Click on the link http://kent.skoool.co.uk/keystage3.aspx?id=63
• Listen and watch lessons 18, 19, 22 and 23 on the female and male reproductive system, sexual intercourse and fertilisation.
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