ROUTERA

Heredity and Evolution

Class 10th Science Chapter Case Study

Case Study 1: Mendel's Pea Plant Experiments

Case Description:
Gregor Mendel conducted experiments with pea plants to study the inheritance of traits. He observed how traits such as height (tall vs. short) and color (yellow vs. green) were passed from one generation to the next. Mendel formulated the laws of inheritance, including the Law of Segregation and the Law of Independent Assortment, which explained how alleles segregate during gamete formation.

MCQs:

  1. What characteristic did Mendel use to differentiate between tall and short pea plants?

    • A) Leaf color
    • B) Flower color
    • C) Plant height
    • D) Seed shape

  2. Which of the following statements is true about Mendel’s Law of Segregation?

    • A) Alleles do not separate during gamete formation.
    • B) Alleles segregate independently of each other.
    • C) Each gamete carries two alleles for each trait.
    • D) Each gamete carries only one allele for each trait.

  3. In Mendel's experiments, the tall pea plant trait is considered:

    • A) Recessive
    • B) Dominant
    • C) Codominant
    • D) Incomplete dominant

  4. If a homozygous tall plant (TT) is crossed with a homozygous short plant (tt), what will be the genotype of the F1 generation?

    • A) TT
    • B) Tt
    • C) tt
    • D) Tt and tt

Case Study 2: The Role of Chromosomes in Inheritance

Case Description:
Chromosomes are structures within cells that contain DNA and genes. Each species has a characteristic number of chromosomes. For instance, humans have 46 chromosomes, organized in 23 pairs. During reproduction, chromosomes from each parent combine, leading to the formation of a zygote with a complete set of chromosomes, half from each parent.

MCQs:

  1. How many chromosomes do humans have in total?

    • A) 23
    • B) 46
    • C) 92
    • D) 30

  2. What is the term used for the different forms of a gene?

    • A) Genotype
    • B) Phenotype
    • C) Alleles
    • D) Chromatids

  3. What process leads to the formation of gametes with half the number of chromosomes?

    • A) Mitosis
    • B) Meiosis
    • C) Fertilization
    • D) Replication

  4. In humans, which chromosomes determine the sex of an individual?

    • A) Autosomes
    • B) Homologous chromosomes
    • C) Sex chromosomes
    • D) Centromeres

Case Study 3: Natural Selection and Adaptation

Case Description:
Natural selection is a key mechanism of evolution proposed by Charles Darwin. It explains how organisms better adapted to their environment tend to survive and produce more offspring. For example, the peppered moth in England showed a color change from light to dark during the Industrial Revolution, demonstrating natural selection in action as darker moths were better camouflaged against pollution-darkened trees.

MCQs:

  1. Who proposed the theory of natural selection?

    • A) Gregor Mendel
    • B) Charles Darwin
    • C) Jean-Baptiste Lamarck
    • D) Alfred Russel Wallace

  2. What does natural selection primarily act on?

    • A) Genotypes
    • B) Phenotypes
    • C) Gametes
    • D) Chromosomes

  3. In the case of the peppered moth, what caused the shift in population color?

    • A) Genetic mutation
    • B) Environmental changes
    • C) Migration
    • D) Artificial selection

  4. Which of the following best describes adaptation?

    • A) Change in genetic material
    • B) Change in behavior
    • C) Characteristics that improve survival and reproduction
    • D) Any random change in organisms

Case Study 4: Genetic Disorders and Inheritance

Case Description:
Genetic disorders can be inherited through dominant or recessive alleles. For instance, cystic fibrosis is caused by a recessive allele, meaning that an individual must inherit two copies of the allele to express the disorder. In contrast, Huntington's disease is caused by a dominant allele, where only one copy is needed for the disorder to manifest.

MCQs:

  1. What type of inheritance pattern does cystic fibrosis follow?

    • A) Codominance
    • B) Incomplete dominance
    • C) Recessive inheritance
    • D) Dominant inheritance

  2. Which of the following is true about Huntington's disease?

    • A) It is caused by a recessive allele.
    • B) It requires two copies of the allele to manifest.
    • C) It is caused by a dominant allele.
    • D) It is not inherited.

  3. If both parents are carriers of a recessive genetic disorder, what is the probability of having an affected child?

    • A) 25%
    • B) 50%
    • C) 75%
    • D) 0%

  4. What is the genotype of an individual with cystic fibrosis?

    • A) AA
    • B) Aa
    • C) aa
    • D) AB

Case Study 5: Fossil Records and Evolutionary Evidence

Case Description:
Fossils provide important evidence for the theory of evolution. They help scientists understand how organisms have changed over time. The fossil record shows transitional forms, such as Archaeopteryx, which exhibits both avian and reptilian characteristics, indicating the evolutionary link between birds and reptiles.

MCQs:

  1. What does the fossil record primarily provide evidence for?

    • A) Creationism
    • B) Evolution
    • C) Genetic drift
    • D) Adaptation

  2. Which of the following is a transitional fossil that shows characteristics of both birds and reptiles?

    • A) Tyrannosaurus rex
    • B) Archaeopteryx
    • C) Pterodactyl
    • D) Velociraptor

  3. How do fossils help scientists in studying evolution?

    • A) They show current species.
    • B) They provide genetic information.
    • C) They reveal the age and development of organisms over time.
    • D) They explain reproduction methods.

  4. Which type of fossil is formed from the impressions of organisms?

    • A) Cast
    • B) Mold
    • C) Trace
    • D) True form