B1 Variation and inheritance 0.0 / 5 ? BiologyInherited characteristics, Chromosomes, Genetic variation, A monohybrid cross, Inherited disordersGCSEOCR Created by: Nicole10Created on: 18-11-15 19:42 Inherited human characteristics can be -------- or ---------- Dominant or recessive 1 of 21 What are alleles? Different versions of the same gene 2 of 21 What do dominant and recessive characteristics depend on? Dominant and recessive alleles 3 of 21 When are dominant and recessive alleles expressed? Dominant alleles - when present & Recessive alleles- only in the absence of the dominant allele 4 of 21 How many pairs of chromosomes do human cells have? 23 pairs 5 of 21 What determines sex in mammals? Sex chromosomes 6 of 21 Name of female sex chromosomes... ** 7 of 21 Name of male sex chromosomes... XY 8 of 21 Sperm will carry which chromosome? Either X or Y 9 of 21 Eggs will carry which chromosome? X 10 of 21 Why is there an equal chance of the offspring being male or female? There is a random chance of which sperm fertilises an egg 11 of 21 Genetic variation is caused by... Mutations (random changes in genes or chromosomes) 12 of 21 Genetic variation is caused by... Rearrangement of genes during the formation of gametes 13 of 21 Genetic variation is caused by... Fertilisation (results in a zygote with alleles from mother and father) 14 of 21 What does a monohybrid cross involve? Involves only one pair of characteristics controlled by a single cell (1 dominant and 1 recessive allele) 15 of 21 What does homozygous mean? Having identical alleles 16 of 21 What does heterozygous mean? Having different alleles 17 of 21 What is a person's genotype? Their genetic make-up 18 of 21 What is a person's phenotype? Which alleles are expressed 19 of 21 What causes inherited disorders? Faulty genes (most are recessive) 20 of 21 How do you predict the probability of inheriting certain disorders? By interpreting genetic diagrams 21 of 21
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