1What is inheritance?
The biological process by which traits are passed from parents to offspring
2What is genetics?
The scientific study of inherited traits and their variation
3Who is considered the father of genetics?
Gregor Mendel
4What organism did Mendel use in his experiments?
Pea plants (Pisum sativum)
5Why were Mendel’s experiments important?
They revealed predictable patterns of inheritance
6What does Mendelian genetics study?
Inheritance of single genes with predictable patterns (simple dominance)
7What does non-Mendelian genetics describe?
Inheritance patterns that do not follow simple Mendelian ratios (e.g., incomplete dominance, codominance, epistasis, polygenic traits)
8What is a single-gene trait?
A trait controlled mainly by one gene
9What is an allele?
An alternative form of a gene
10What does the Law of Segregation state?
Each individual has two alleles that separate during gamete formation
11When do alleles segregate?
During meiosis
12How many alleles does each gamete receive?
One allele per gene
13What does the Law of Independent Assortment state?
Alleles of different genes segregate independently into gametes
14When does independent assortment apply?
When genes are on different chromosomes (or far apart)
15What does independent assortment increase?
Genetic variation
16What is genotype?
The allelic makeup of an organism
17What is phenotype?
The observable traits of an organism
18What does the Law of Dominance state?
Dominant alleles mask recessive alleles in heterozygotes
19How are dominant alleles written?
Uppercase letters
20How are recessive alleles written?
Lowercase letters
21What is a monohybrid cross?
A cross involving one trait
22What phenotypic ratio results from Aa × Aa?
3:1
23What genotypic ratio results from Aa × Aa?
1:2:1
24What is a dihybrid cross?
A cross involving two traits
25What phenotypic ratio results from AaBb × AaBb?
9:3:3:1
26What is autosomal dominant inheritance?
One mutated allele causes disease
27Give examples of autosomal dominant diseases
Huntington’s disease, Marfan syndrome, neurofibromatosis
28What is autosomal recessive inheritance?
Two mutated alleles are required for disease
29Who are carriers in autosomal recessive disorders?
Heterozygous individuals
30Give examples of autosomal recessive diseases
Cystic fibrosis, sickle cell anaemia, PKU
31What is X-linked inheritance?
Inheritance of traits on the X chromosome
32Why are males more affected by X-linked diseases?
They have only one X chromosome
33Give examples of X-linked disorders
Haemophilia, Duchenne muscular dystrophy, red-green colour blindness
34What is incomplete dominance?
Heterozygotes show an intermediate phenotype
35What is the classic example of incomplete dominance?
Snapdragon flower colour
36What phenotypic ratio occurs in F2 snapdragon crosses?
1 red : 2 pink : 1 white
37What is codominance?
Both alleles are fully expressed in heterozygotes
38What is a classic codominance example?
AB blood type
39What are multiple alleles?
More than two alleles exist for a gene in a population
40How many alleles can an individual have?
Two
41What system demonstrates multiple alleles?
ABO blood group system
42What alleles exist in the ABO system?
IA, IB, and i
43Which alleles are codominant?
IA and IB
44Which allele is recessive?
i
45What blood type results from IAIB?
AB
46What blood type results from ii?
O
47What is polygenic inheritance?
Traits controlled by multiple genes
48What type of variation do polygenic traits show?
Continuous variation
49What distribution do polygenic traits follow?
Normal (bell curve) distribution
50Give examples of polygenic traits
Height, IQ, blood pressure
51What is heritability?
The proportion of variation in a trait due to genetic differences
52Are polygenic traits purely genetic?
No, environment also contributes
53What is pleiotropy?
One gene affects multiple traits
54What disease demonstrates pleiotropy?
Sickle cell anaemia
55What is epistasis?
One gene masks or modifies another gene
56What is a classic epistasis example?
Labrador coat colour