10th Science - Second Mid Term Test 2024
Solved Question Paper
Part - I (10 x 1 = 10)
Choose the correct answer:
1. When a sound wave travels through air, the air particles
2. The frequency, which is audible to the human ear is
3. Artificial radioactivity was discovered by
4. _______ isotope is used for the treatment of cancer.
5. Photolysis is a decomposition reaction caused by
6. The pH of a solution is 3. Its [OH⁻] concentration is
Explanation: We know that \( [H^+][OH^-] = 1 \times 10^{-14} \). Given pH = 3, so \( [H^+] = 10^{-3} \) M. Therefore, \( [OH^-] = \frac{1 \times 10^{-14}}{10^{-3}} = 1 \times 10^{-11} \) M.
7. The 'use and disuse theory' was proposed by
8. Paleontologists deal with
9. DNA fingerprinting is based on the principle of identifying _______ sequences of DNA.
10. Pusa Komal is a disease resistant variety of
Part - II (5 x 2 = 10)
Answer any 5 questions. (Q.No.18 is compulsory)
11. What is a longitudinal wave?
12. Match:
| 1. Infrasonic | a) Compressions |
| 2. Echo | b) 22 kHz |
| 3. Ultrasonic | c) 10 Hz |
| 4. High pressure region | d) Ultrasonography |
| 1. Infrasonic | c) 10 Hz |
| 2. Echo | d) Ultrasonography |
| 3. Ultrasonic | b) 22 kHz |
| 4. High pressure region | a) Compressions |
13. In Japan, some of the new born children are having congenital diseases. Why?
14. Define combination reaction. Give example.
Example: Carbon burning in oxygen to form carbon dioxide. \[ C (s) + O_2 (g) \rightarrow CO_2 (g) \]
15. a) Which organism is considered to be the fossil bird?
b) What is the study of fossils called?
b) The study of fossils is called Paleontology.
16. What are transgenic organisms?
17. Name the types of stem cells.
- Embryonic stem cells: Found in the early-stage embryo. They are pluripotent, meaning they can develop into any cell type of the body.
- Adult stem cells: Found in various tissues of the body. They are multipotent, meaning they can develop into a limited range of cell types.
18. Two observers are stationed in two boats 4.5 km apart. A sound signal sent by one, under water, reaches the other after 3 seconds. What is the speed of sound in the water?
- Distance (d) = 4.5 km = 4500 m
- Time (t) = 3 s
Calculation: \[ \text{Speed} = \frac{4500 \text{ m}}{3 \text{ s}} = 1500 \text{ m/s} \] The speed of sound in the water is 1500 m/s.
Part - III (4 x 4 = 16)
Answer any 4 questions. (Q.No.25 is compulsory)
19. a) Why does sound travel faster on a rainy day than on a dry day?
b) Name three animals, which can hear ultrasonic vibrations.
b) Three animals that can hear ultrasonic vibrations are:
- Bats
- Dolphins
- Dogs
20. a) Give the function of control rods in a nuclear reactor.
b) What is stellar energy?
b) Stellar energy is the energy produced by stars. This energy is generated through the process of nuclear fusion, where light atomic nuclei (primarily hydrogen) fuse together under immense temperature and pressure to form heavier nuclei (like helium), releasing a tremendous amount of energy in the process.
21. Explain a) Precipitation Reactions b) Neutralization Reactions
Example: When a solution of silver nitrate is mixed with a solution of sodium chloride, a white precipitate of silver chloride is formed. \[ AgNO_3(aq) + NaCl(aq) \rightarrow AgCl(s) \downarrow + NaNO_3(aq) \] b) Neutralization Reaction: A neutralization reaction is a chemical reaction between an acid and a base. It results in the formation of a salt and water. The H⁺ ions from the acid react with the OH⁻ ions from the base to form water.
Example: The reaction between hydrochloric acid (a strong acid) and sodium hydroxide (a strong base) forms sodium chloride (a salt) and water. \[ HCl(aq) + NaOH(aq) \rightarrow NaCl(aq) + H_2O(l) \]
22. a) Why is Archaeopteryx considered to be a connecting link?
b) How can you determine the age of the fossils?
- Reptilian features: Jaws with teeth, a long bony tail, and claws on its wings.
- Avian (bird-like) features: Feathers on its body and wings, and a wishbone (furcula).
b) The age of fossils can be determined by two main methods:
- Relative Dating: This method determines the relative age of fossils by examining their position in layers of rock (strata). Fossils found in deeper layers are generally older than those in upper layers.
- Absolute Dating (Radiometric Dating): This method determines the actual age of a fossil in years. It is based on the decay of radioactive isotopes present in the rocks around the fossil. For example, Carbon-14 dating is used for relatively young fossils, while Potassium-Argon dating is used for older ones.
23. a) Differentiate between Outbreeding and Inbreeding.
b) Differentiate between Undifferentiated cells and Differentiated cells.
| Feature | Outbreeding | Inbreeding |
|---|---|---|
| Definition | Mating of unrelated individuals. | Mating of closely related individuals. |
| Genetic Effect | Increases heterozygosity. | Increases homozygosity. |
| Outcome | Often results in hybrid vigour (heterosis). | Can lead to inbreeding depression and expression of harmful recessive traits. |
| Feature | Undifferentiated Cells | Differentiated Cells |
|---|---|---|
| Definition | Unspecialized cells that can divide and renew themselves. | Specialized cells that have a specific function. |
| Potency | Can develop into one or more types of specialized cells (e.g., stem cells). | Have a specific structure and function and have lost their ability to differentiate. |
| Example | Embryonic stem cells, adult stem cells. | Nerve cells, muscle cells, skin cells. |
24. What are the effects of hybrid vigour in animals?
- Increased Growth Rate: Hybrid animals often grow faster and reach market weight sooner.
- Higher Yield: Increased production of milk, meat, or eggs compared to the parent breeds.
- Improved Fertility: Higher conception rates and larger litter sizes.
- Greater Disease Resistance: Hybrids are often more robust and less susceptible to diseases.
- Better Adaptability: Enhanced ability to thrive in various environmental conditions.
25. a) A solution has a pOH of 11.76. What is the pH of this solution?
b) Calculate the pH of 1.0 x 10⁻⁴ molar solution of HNO₃?
We know the relationship between pH and pOH is: \[ pH + pOH = 14 \] Substituting the given value: \[ pH + 11.76 = 14 \] \[ pH = 14 - 11.76 \] \[ pH = 2.24 \] The pH of the solution is 2.24.
b) Given: Concentration of \(HNO_3\) is \(1.0 \times 10^{-4}\) M.
Nitric acid (\(HNO_3\)) is a strong acid, so it completely ionizes in water. \[ HNO_3 \rightarrow H^+ + NO_3^- \] Therefore, the concentration of \(H^+\) ions is equal to the concentration of the acid. \[ [H^+] = 1.0 \times 10^{-4} \text{ M} \] The formula for pH is: \[ pH = -\log[H^+] \] \[ pH = -\log(1.0 \times 10^{-4}) \] \[ pH = -(-4) \] \[ pH = 4 \] The pH of the solution is 4.
Part - IV (2 x 7 = 14)
Answer all the questions in detail.
26. a) Compare the properties of alpha, beta and gamma radiations.
Comparison of Alpha (α), Beta (β), and Gamma (γ) Radiations
| Property | Alpha (α) Particle | Beta (β) Particle | Gamma (γ) Ray |
|---|---|---|---|
| Nature | Helium nucleus (\(^{4}_{2}\text{He}\)) | Electron (\(^{0}_{-1}\text{e}\)) | Electromagnetic wave (Photon) |
| Charge | Positive charge (+2e) | Negative charge (-1e) | No charge (Neutral) |
| Mass | High (\(6.64 \times 10^{-27}\) kg) | Low (\(9.11 \times 10^{-31}\) kg) | No rest mass |
| Ionizing Power | Very high (about 100 times β, 10000 times γ) | Moderate (less than α) | Very low |
| Penetrating Power | Very low (stopped by a sheet of paper) | Moderate (stopped by a thin aluminum sheet) | Very high (requires thick lead or concrete to stop) |
| Speed | About 1/10 to 1/20 of the speed of light | Up to 9/10 of the speed of light | Travels at the speed of light |
| Effect of Electric/Magnetic Field | Deflected towards the negative plate/pole | Deflected towards the positive plate/pole (more than α) | Not deflected |
(OR)
b) What is a chemical equilibrium? What are its characteristics?
Chemical Equilibrium
Chemical equilibrium is a state in a reversible chemical reaction where the rate of the forward reaction (reactants forming products) is equal to the rate of the reverse reaction (products forming reactants). At this point, the concentrations of reactants and products remain constant over time, and there is no net change in the composition of the system.
Characteristics of Chemical Equilibrium:
- Dynamic Nature: Equilibrium is dynamic, not static. Both forward and reverse reactions continue to occur, but at equal rates, so there is no overall change.
- Constant Concentrations: The concentrations of all reactants and products become constant at equilibrium.
- Reversibility: Equilibrium can only be attained in reversible reactions.
- Closed System: A state of chemical equilibrium can only be reached in a closed system, where no substances can enter or leave.
- Attainable from Either Direction: Equilibrium can be approached from either the reactants' side or the products' side.
- Effect of a Catalyst: A catalyst increases the rates of both the forward and reverse reactions equally. Therefore, a catalyst helps in attaining equilibrium faster but does not alter the position of the equilibrium or the equilibrium constant.
27. a) i) How do you differentiate homologous organs from analogous organs?
ii) Natural selection is a driving force for evolution-How?
i) Differentiation between Homologous and Analogous Organs
| Basis of Difference | Homologous Organs | Analogous Organs |
|---|---|---|
| Origin and Structure | Similar basic structure and developmental origin. | Different basic structure and developmental origin. |
| Function | Perform different functions. | Perform similar functions. |
| Evolution | Indicate divergent evolution (common ancestor, adapted to different needs). | Indicate convergent evolution (different ancestors, adapted to similar needs). |
| Example | Forelimbs of a human, bat, whale, and cheetah. | Wings of an insect and a bird. |
ii) Natural Selection as a Driving Force for Evolution
Natural selection, a concept proposed by Charles Darwin, is the primary mechanism and driving force behind evolution. It works through the following steps:
- Variation: Within any population, individuals exhibit variations in their traits (e.g., size, color, resistance to disease). These variations arise from genetic mutations and recombination.
- Overproduction: Organisms tend to produce more offspring than can survive, leading to a "struggle for existence."
- Survival of the Fittest: Individuals with variations that make them better adapted to their environment are more likely to survive, compete for resources, and reproduce. This is often referred to as "survival of the fittest."
- Inheritance: The advantageous traits of the surviving individuals are passed on to their offspring.
- Gradual Change: Over many generations, the frequency of these favorable traits increases in the population, while unfavorable traits become less common. This gradual accumulation of changes leads to the evolution of new species.
For example, the evolution of long necks in giraffes can be explained by natural selection. Ancestral giraffes had varied neck lengths. Those with slightly longer necks could reach more leaves, had a survival advantage, and reproduced more, passing the long-neck trait to their offspring. Over generations, this led to the very long necks we see today.
(OR)
b) i) Differentiate: Somatic gene therapy and Germ line gene therapy
ii) Biofortification may help in removing hidden hunger. How?
i) Differentiation between Somatic and Germ Line Gene Therapy
| Basis of Difference | Somatic Gene Therapy | Germ Line Gene Therapy |
|---|---|---|
| Target Cells | Body cells (somatic cells) like bone marrow cells, skin cells, etc. | Reproductive cells (germ cells) like sperm or eggs, or early embryos. |
| Heritability | The genetic changes are not passed on to the next generation. | The genetic changes are heritable and are passed on to all subsequent generations. |
| Purpose | To treat a genetic disease in a single individual. | To permanently correct a genetic defect in a family line. |
| Ethical Concerns | Considered ethically more acceptable for treating diseases. | Raises significant ethical concerns due to permanent changes in the human gene pool. It is currently banned in most countries for human use. |
ii) How Biofortification helps in removing Hidden Hunger
Hidden hunger refers to a chronic lack of essential micronutrients (vitamins and minerals) in a diet, even if a person consumes enough calories. It can lead to serious health problems, impaired development, and reduced productivity.
Biofortification is the process of increasing the nutritional value of food crops through conventional plant breeding or modern biotechnology. It addresses hidden hunger directly at its source by making staple foods more nutritious. Here's how it helps:
- Enhancing Staple Foods: Biofortification focuses on staple crops like rice, wheat, maize, and beans, which are consumed in large quantities by populations, especially in developing countries. By enriching these staples, it ensures that people get more vitamins and minerals without changing their dietary habits.
- Cost-Effective and Sustainable: Once a biofortified crop is developed, it can be distributed and grown by farmers year after year. It is a one-time investment that can provide a sustainable source of micronutrients for entire communities, making it more cost-effective than recurring interventions like distributing supplements.
- Targeted Nutrient Improvement: Specific micronutrient deficiencies can be targeted. For instance:
- Golden Rice: Genetically engineered to produce beta-carotene, a precursor of Vitamin A, to combat Vitamin A deficiency.
- Iron-biofortified Beans and Pearl Millet: Bred to have higher iron content to fight iron-deficiency anemia.
- Zinc-biofortified Wheat and Rice: Developed to increase zinc intake, crucial for immune function and growth.
By making staple foods themselves the source of better nutrition, biofortification is a powerful and practical strategy to combat hidden hunger on a large scale.