IGCSE biology!!!!

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Pink_Sparkles
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#1
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#1
hi there !!!
i wanted to ask if anyone can explain the following topics or paste some pics or links
*cordination in plants and animals.
*natural selection and selective breeding
*meiosis and mitosis
and if u guys don't understand anything feel free to ask on this thread
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Pink_Sparkles
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can any one help me please!!!!!
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2567523
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(Original post by shahida sulaiman)
can any one help me please!!!!!
Meiosis happens for making SEX CELLS ONLY. Mitosis is for producing body cells and asexual reproduction.
Meiosis:
1. There are 4 chromosomes in the parent cell (2 homologous (same) pairs)
2. EACH CHROMOSOME COPIES ITSELF (now there are 8 chromatids)
3. First division: ONE CHROMOSOME (each containing 2 chromatids) from each homologous pair goes to each daughter cell (there are 2 daughter cells)
4. Second division: the CHROMATIDS ARE SEPERATED and one chromatid from each chromosome ends up in each daughter cell
5. So now u have 4 daughter cells
This is How sex cells are formed

Mitosis:
There are 4 chromosomes in the parent cell. Each chromosome copies itself. The cell divides into 2 new ones. Each daughter cell has a copy of all the chromosomes.
Remember PMAT.
1. Prophase
The nuclear membrane of the cell breaks down
2. Metaphase
The chromatids are attached to SPINDLE FIBRES in the cell. They are attached to it by their CENTROMERE
3. Anaphase
The spindle fibres SHORTEN and pull the chromatids of each chromosome to opposite ends of the cell (so imagine u have 4 chromatids on each side now)
4. Telophase
Two nuclei form at the likes of each cell (so imagine the cell splitting to form 2 new ones). Each new cell has a copy of a chromosome from the parent cell
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2567523
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It helps if u look in the IGCSE edexcel bio book chapter 17 for images. The visuals are helpful
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Pink_Sparkles
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and the others
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Victoria Jolee
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(Original post by shahida sulaiman)
hi there !!!
i wanted to ask if anyone can explain the following topics or paste some pics or links
*cordination in plants and animals.
*natural selection and selective breeding
*meiosis and mitosis
and if u guys don't understand anything feel free to ask on this thread
are you taking core or extended?
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Pink_Sparkles
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(Original post by Victoria Jolee;[url="tel:64813715")
64813715[/url]]are you taking core or extended?
extended
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Victoria Jolee
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#8
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(Original post by shahida sulaiman)
extended
check out https://www.youtube.com/watch?v=GJJAktyCrbE and the channel videos
and https://igcserevision.wordpress.com/
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