Course review
Review each learning objective in this topic, then open its concept explanation or question set.
Learning objective
• Haploid gametes fuse during fertilization to form a diploid zygote • Diploid organisms usually carry two alleles for each autosomal gene
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Learning objective
• Genetic crosses track parental, F1, and F2 generations using Punnett grids • Flowering plant crosses control pollen transfer to study inheritance ratios
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Learning objective
• Genotype is the allele combination inherited for a gene or genes • Homozygous genotypes have matching alleles; heterozygous genotypes have different alleles
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Learning objective
• Phenotype is the observable characteristic or trait • Phenotype can be determined by genotype, environment, and their interaction
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Learning objective
• Dominant alleles are expressed in heterozygotes • Recessive alleles are expressed when no dominant allele masks them
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Learning objective
• Phenotypic plasticity is environment-driven phenotype change without genotype change • It depends on altered gene expression and can be adaptive
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Learning objective
• PKU is an autosomal recessive disorder affecting phenylalanine metabolism • Low-phenylalanine diet and newborn screening reduce harmful effects
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Learning objective
• SNPs are single-base differences that can create different alleles • Populations can have multiple alleles, but diploid individuals carry at most two
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Learning objective
• ABO blood group is controlled by IA, IB, and i alleles • IA and IB are codominant; i is recessive, producing four blood phenotypes
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Learning objective
• Codominance expresses both heterozygous alleles, as in AB blood type • Incomplete dominance gives an intermediate heterozygote phenotype
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Learning objective
• Human chromosomal sex is usually determined by XX or XY chromosome combination • The SRY/TDF region on the Y chromosome directs testis development
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Learning objective
• Haemophilia is an X-linked recessive blood-clotting disorder • Carrier females and affected males are represented with X-linked allele notation
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Learning objective
• Pedigree charts show family inheritance across generations • Patterns help infer autosomal dominant, autosomal recessive, or sex-linked inheritance
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Learning objective
• Continuous variation often results from polygenic inheritance plus environment • Human skin colour, height, and body mass show many intermediate phenotypes
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Learning objective
• Box-and-whisker plots summarize non-normal continuous data • They show median, quartiles, interquartile range, maximum/minimum, and outliers
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Learning objective
• Alleles segregate as homologous chromosomes separate during meiosis • Unlinked genes assort independently through random bivalent orientation
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Learning objective
• Dihybrid crosses track inheritance of two genes simultaneously • Unlinked autosomal genes can produce 9:3:3:1 F2 or 1:1:1:1 test-cross ratios
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Learning objective
• Genome databases identify human gene loci and polypeptide products • Genes on different chromosomes are unlinked; close loci on one chromosome can be linked
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Learning objective
• Linked autosomal genes are on the same non-sex chromosome • Linked genes tend to be inherited together unless crossing over occurs between loci
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Learning objective
• Recombinants have allele combinations different from parental chromosomes • Crossing over between linked genes produces fewer recombinants than parental types
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Learning objective
• Chi-squared tests whether observed genetic data fit expected ratios • Use observed/expected values, degrees of freedom, and p = 0.05 significance
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