Biology B1.2

Flashcards by raffia.khalid99, updated more than 1 year ago
Created by raffia.khalid99 over 5 years ago


Flashcards covering OCR 21st Century Science Biology B1 Module - part 2 of 4, Inheritance (B1.2)

Resource summary

Question Answer
How many chromosomes do human body cells contain? 46 (23 from each parent)
How many chromosomes do human sex cells contain? 23 (e.g. the egg cell contains 1 chromosome from each pair in the human body cell, as does the sperm cell)
What are alleles? Each of two (or more) different versions of the same gene
What are homozygous genes? Homozygous genes are genes with two or more of the same alleles
What are heterozygous genes? Genes where the two or more alleles are different from eachother
How do the sexual reproduction genes from each parent produce variation in offspring? Because each the egg only contains one chromosome from each pair of chromosome, as does the sperm cell. When they come together + produce offspring, they produce a random combination of chromosomes which produces variatoin.
Why do siblings differ from each other? Because they have a different combination of paternal and maternal alleles
What traits will somebody show if they have...a.) one dominant allele and one recessive allele b.) two recessive alleles c.) two dominant alleles a.) the dominant allele's characteristic b.) the recessive allele's characteristic c.) the dominant allele's characteristic
How do human males determine the sex of the offspring? Human males have an X and a Y chromosome. If they pass on the Y chromosome, the offspring will develop testes, making the offspring male.
What's the difference between the genotype and the phenotype? Genotype - describing the genetic make up of an organism (combination of alleles) Phenotype - the physical appearance of an organism (the observable characteristic)
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