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Here’s a list of essay questions and answers related to the topic of Inheritance that could appear in a trial SPM 2024 Biology exam. These are based on the SPM Biology syllabus and common question patterns.

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### Question 1:
Explain the principles of inheritance in Mendel’s experiments and how they apply to human genetics.

Answer:
1. Mendel’s Principles of Inheritance:
- Mendel conducted experiments on pea plants and established three principles:
- Law of Segregation: Each organism has two alleles for each trait, which separate during gamete formation. Offspring inherit one allele from each parent.
- Law of Independent Assortment: Alleles for different traits are distributed independently of one another during gamete formation.
- Dominance: Some alleles are dominant and mask the expression of recessive alleles.

2. Application to Human Genetics:
- Humans inherit traits through genes located on chromosomes.
- For example, blood type is determined by multiple alleles (A, B, O), where A and B are codominant, and O is recessive.
- Genetic disorders like sickle cell anemia or cystic fibrosis follow Mendelian inheritance patterns (autosomal recessive or dominant).

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### Question 2:
Describe the differences between sex-linked inheritance and autosomal inheritance, using examples.

Answer:
1. Sex-Linked Inheritance:
- Genes are located on the sex chromosomes (X or Y).
- Example: Hemophilia and color blindness are X-linked recessive disorders.
- Males are more likely to express X-linked traits because they have only one X chromosome.

2. Autosomal Inheritance:
- Genes are located on autosomes (non-sex chromosomes).
- Example: Cystic fibrosis is an autosomal recessive disorder.
- Both males and females are equally likely to inherit autosomal traits.

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### Question 3:
Explain how a monohybrid cross can be used to predict the genotype and phenotype ratios of offspring.

Answer:
1. Monohybrid Cross:
- A cross between two individuals that differ in one trait (e.g., tall vs. short pea plants).
- Parental genotypes: TT (homozygous dominant) x tt (homozygous recessive).

2. Punnett Square:
- Offspring genotype: 100% Tt (heterozygous).
- Offspring phenotype: 100% tall (dominant trait).

3. F2 Generation:
- Cross two F1 offspring (Tt x Tt).
- Genotype ratio: 1 TT : 2 Tt : 1 tt.
- Phenotype ratio: 3 tall : 1 short.

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### Question 4:
Discuss the importance of genetic variation in a population and how it is maintained through meiosis and fertilization.

Answer:
1. Importance of Genetic Variation:
- Allows populations to adapt to changing environments.
- Reduces the risk of genetic disorders due to inbreeding.

2. Meiosis:
- Produces gametes with half the chromosome number.
- Crossing over during prophase I and independent assortment during metaphase I create genetic diversity.

3. Fertilization:
- Combines genetic material from two parents, increasing variation in offspring.

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### Question 5:
Explain how mutations can lead to genetic disorders and provide examples.

Answer:
1. Mutations:
- Changes in the DNA sequence that can alter gene function.
- Can be caused by environmental factors (e.g., radiation) or occur spontaneously.

2. Genetic Disorders:
- Sickle Cell Anemia: Caused by a point mutation in the hemoglobin gene, leading to abnormal red blood cells.
- Down Syndrome: Caused by nondisjunction during meiosis, resulting in an extra chromosome 21.

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### Question 6:
Describe the role of DNA and chromosomes in inheritance.

Answer:
1. DNA:
- Contains genetic instructions for the development and functioning of organisms.
- Composed of nucleotides (A, T, C, G) that form genes.

2. Chromosomes:
- Structures made of DNA and proteins that carry genes.
- Humans have 46 chromosomes (23 pairs), including sex chromosomes (XX or XY).

3. Inheritance:
- Offspring inherit one set of chromosomes from each parent.
- Genes on chromosomes determine traits like eye color, height, and susceptibility to diseases.

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