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What does the Heredity and Variation revision sheet cover?

Heredity, Variation, Gene, The words, fixed first, DNA, Chromosome, DNA, and what it does, Sources of variation, Mutation, Where variation comes from, Inherited against acquired, Inherited.

Is this for Class 9 Maharashtra SSC Science?

Yes, it is written for the Maharashtra SSC Science syllabus.

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Heredity and Variation — Class 9 Maharashtra SSC Science revision notes

A 4-page visual revision sheet for Heredity and Variation, written for Class 9 Maharashtra SSC Science. Formulas, diagrams and the traps that cost marks, laid out to be read the night before rather than the term before. Free, and it opens inside CapCompass.

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Heredity and Variation in one look

what is passed on, what is not, and the molecule that carries the instructions

The words, fixed first

heredity is the passing of characters from parents to offspring across generations
variation is the differences between individuals of the same species, including between brothers and sisters
a chromosome is a thread of DNA in the nucleus, and humans have 23 pairs
a gene is a segment of DNA carrying the instruction for one character, and its alternative forms are alleles
inherited characters are carried in the DNA: eye colour, blood group, height and the shape of features
acquired characters are not inherited, since a change during a lifetime does not alter the DNA of the gametes

DNA, and what it does

DNA is the molecule that carries the genetic instructions, shaped as a double helix, two strands wound about each other
the two strands are held by pairs of bases, and the pairing is fixed: A with T and G with C
because the pairing is fixed, each strand carries the full information, and the molecule can copy itself exactly
that copying is what allows a character to be passed on unchanged through cell division
a mistake in copying is a mutation, and it is the only source of genuinely new variation
genes direct the making of proteins, and the proteins are what actually produce the character

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What this Heredity and Variation sheet covers

Heredity
Variation
Gene
The words, fixed first
DNA
Chromosome
DNA, and what it does
Sources of variation
Mutation
Where variation comes from
Inherited against acquired
Inherited
Acquired
Sorting characters
Evolution
Natural selection
Fossil
Evolution, in outline
Terms in this chapter
Traps that cost marks
Tricks that save time

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