Class 10 (Science assignment)

 

Heredity

Heredity is the process by which characteristics are passed from parents to their offspring. The similarities and differences between parents and children are due to heredity and variation. The basic unit of heredity is called a gene. Genes are segments of DNA (Deoxyribonucleic Acid) that carry information for specific traits such as eye colour, blood group, height, and other characteristics.

Genes are located on chromosomes, which are thread-like structures found inside the nucleus of a cell. Humans have 46 chromosomes arranged in 23 pairs. Among them, 22 pairs are called autosomes and one pair is called sex chromosomes. Sex chromosomes determine the sex of an individual. Females usually have XX chromosomes, while males usually have XY chromosomes.

The scientist Gregor Mendel is known as the father of genetics because of his experiments on pea plants. He discovered the basic principles of inheritance. Mendel explained that traits are controlled by factors (now called genes) and that some traits may be dominant while others may be recessive. A dominant trait appears even when only one dominant gene is present, whereas a recessive trait appears only when both genes are recessive.

Variation means the differences found among individuals of the same species. Variations occur due to genetic changes, environmental factors, and the combination of genes during reproduction. Variations are important because they help organisms adapt to changing environments and play a role in evolution.

Multiple Choice Questions (MCQs)

1. What is the basic unit of heredity?
A. Cell
B. Tissue
C. Gene
D. Chromosome
2. Genes are made up of:
A. Protein
B. DNA
C. Fat
D. Carbohydrate
3. Who is known as the father of genetics?
A. Charles Darwin
B. Isaac Newton
C. Gregor Mendel
D. Louis Pasteur
4. Where are genes located?
A. Ribosomes
B. Cytoplasm
C. Chromosomes
D. Cell wall
5. How many chromosomes are present in a normal human body cell?
A. 23
B. 46
C. 44
D. 48
6. Which chromosome combination is usually found in a human female?
A. XY
B. YY
C. XX
D. XO
7. A trait that appears when only one gene is present is called:
A. Recessive trait
B. Dominant trait
C. Hidden trait
D. Modified trait
8. Differences among individuals of the same species are called:
A. Evolution
B. Adaptation
C. Variation
D. Mutation
9. Mendel performed his experiments on:
A. Wheat plants
B. Pea plants
C. Maize plants
D. Rose plants
10. Variation is important because it helps organisms:
A. Stop reproduction
B. Adapt to environmental changes
C. Lose their characteristics
D. Become identical