General Science – II (Biological Science) – Model Paper II (E/M)
Class: X
Max. Marks: 40
Time: 1.35 Hrs
PART A (Marks: 30)
SECTION I (3 x 2 = 6 Marks)
Instructions:
- Attempt all questions.
- Each question carries 2 marks.
- Answer each question in 1 or 2 sentences.
1. How do you appreciate “stomach as a throwing machine”?
Answer:
The stomach is often referred to as a “throwing machine” because it plays a key role in the process of digestion by breaking down food mechanically and chemically. The muscular walls of the stomach contract and churn the food, mixing it with digestive juices to form chyme. This action resembles the motion of throwing or squeezing, facilitating the digestion process.
2. What is Synapse? What is its importance in the nervous system?
Answer:
A synapse is the junction or connection between two nerve cells (neurons), where signals are transmitted from one neuron to another. It is crucial for communication within the nervous system. Neurotransmitters are released from the axon of one neuron and travel across the synapse to the receptors on the next neuron, enabling signals to move through the nervous system.
3. Write the questions you would ask when you meet the doctor to know about high blood pressure?
Answer:
- What is the normal range of blood pressure for a healthy person?
- What are the causes of high blood pressure (hypertension)?
- How does high blood pressure affect the heart and other organs?
- What lifestyle changes can help control or reduce high blood pressure?
- Are there any medications that I should take to manage hypertension?
- How often should I monitor my blood pressure at home?
SECTION II (3 x 4 = 12 Marks)
Instructions:
- Attempt all questions.
- Each question carries 4 marks.
- Answer each question in 4 to 5 sentences.
4. Mention the various hormones present in plants and write down their uses.
Answer: Plants produce several hormones that regulate growth and development. Key plant hormones include:
- Auxins: Involved in cell elongation, root growth, and responses to light (phototropism).
- Gibberellins: Promote seed germination, stem elongation, and flowering.
- Cytokinins: Stimulate cell division and delay aging of plant tissues.
- Abscisic Acid (ABA): Inhibits growth and helps plants respond to stress (e.g., drought).
- Ethylene: A gas that regulates fruit ripening and leaf abscission (shedding).
These hormones are vital for controlling plant growth, development, and responses to environmental conditions.
5. Study the table below, analyze and answer the questions given below.
| Sl. No. | Plant Name | Type of Vegetative Propagation |
|---|---|---|
| 1 | Mango | Layering |
| 2 | Rose, Hibiscus | Cutting |
| 3 | Jasmine | Grafting |
| 4 | Bryophyllum | Buds on Leaf |
| 5 | Colocasia | Potato |
| 6 | Onion | Bulbs |
Questions:
- How does Bryophyllum spread vegetatively?
Answer:
Bryophyllum spreads vegetatively through the buds that develop along the edges of its leaves. When these buds fall off and land in the soil, they develop into new plants. This is a type of vegetative propagation known as leaf-borne propagation.
- Which part of the Chamgadda (likely Chamagadda or Creeper Plant) is useful for vegetative propagation?
Answer:
In Chamagadda (also known as Creeper Plant), the stem is used for vegetative propagation. The stems can be cut and planted to grow new plants, which is a common method of cutting used in vegetative propagation.
- Identify the methods of artificial vegetative propagation given on the table.
Answer:
The artificial methods of vegetative propagation listed in the table are:
- Layering (used for Mango)
- Cutting (used for Rose, Hibiscus)
- Grafting (used for Jasmine)
These methods involve human intervention to propagate plants that may not reproduce easily through natural means.
- State the uses of vegetative propagation in plant production.
Answer:
Vegetative propagation has several benefits:
- Clonal propagation: It produces genetically identical plants, ensuring uniformity in traits such as fruit quality or flower color.
- Faster reproduction: It speeds up plant production compared to growing from seeds.
- Preservation of desirable traits: It allows for the replication of plants with special characteristics, such as disease resistance or high yield.
- Used in horticulture and agriculture: Common in the production of plants like roses, grapes, and fruit trees.
6. Write the economic benefits of secondary metabolites excreted by plants.
Answer: Secondary metabolites are compounds produced by plants that are not involved in the primary metabolic processes but have significant benefits:
- Medicinal Value: Compounds like alkaloids (e.g., quinine for malaria treatment), terpenes, and flavonoids are used in pharmaceuticals.
- Pesticides and Insecticides: Some secondary metabolites have insect-repellent properties or act as natural pesticides, reducing the need for chemical pesticides.
- Flavor and Fragrance: Compounds like essential oils (e.g., menthol from mint) are used in food, cosmetics, and perfumes.
- Agricultural Use: Certain secondary metabolites are used to enhance plant resistance to pathogens and environmental stress.
SECTION III (2 x 6 = 12 Marks)
Instructions:
- Attempt any two questions.
- Each question carries 6 marks.
- Answer each question in 8 to 10 sentences.
7. What is malnutrition? Write about the diseases caused by malnutrition.
Answer:
Malnutrition is a condition that arises when a person’s diet does not provide the necessary nutrients in the right proportions. It can result from either a deficiency or excess of nutrients.
Diseases caused by malnutrition include:
- Kwashiorkor: Caused by a lack of protein in the diet, leading to swollen abdomen, fatigue, and irritability.
- Marasmus: Caused by a deficiency in both protein and calories, resulting in extreme thinness, stunted growth, and weakened immunity.
- Iron Deficiency Anemia: Caused by a lack of iron, leading to fatigue, weakness, and pale skin.
- Rickets: Caused by a deficiency in vitamin D, calcium, or phosphate, leading to weakened bones in children.
- Scurvy: Caused by a lack of vitamin C, leading to swollen gums, bruising, and fatigue.
8. Explain gas exchange in alveoli with the help of a diagram.
Answer:
Gas exchange in the alveoli occurs in the lungs, where oxygen from the air is transferred to the blood, and carbon dioxide from the blood is transferred to the air to be exhaled.
Process:
- Inhalation: Oxygen-rich air enters the lungs and reaches the alveoli, which are tiny air sacs surrounded by capillaries.
- Oxygen Exchange: Oxygen diffuses through the thin walls of the alveoli and enters the capillaries, where it binds to hemoglobin in red blood cells.
- Carbon Dioxide Exchange: Carbon dioxide, a waste product from cells, moves from the blood into the alveoli to be exhaled.
Diagram:
- Draw a simple diagram showing the alveolus with a capillary next to it.
- Label the oxygen moving into the blood and carbon dioxide moving out.
9. Suggest alternative methods to protect crops from pests based on biological principles.
Answer:
Some alternative methods to protect crops from pests based on biological principles include:
- Biological Control: Using natural predators or parasites to control pest populations. For example, releasing ladybugs to control aphids.
- Pheromone Traps: Using the natural chemical signals (pheromones) produced by pests to trap them and reduce their numbers.
- Crop Rotation: Growing different types of crops in a sequence to prevent pests from becoming established in one type of crop.
- Neem-based Products: Using neem oil, which has insect-repellent properties, as a natural pesticide.
- Resistant Varieties: Planting pest-resistant crop varieties that are naturally less susceptible to certain pests or diseases.
- Companion Planting: Planting certain crops together to deter pests (e.g., planting marigolds with tomatoes to repel nematodes).
PART B (10 x 1 = 10 Marks)
Instructions:
- Choose the correct answer for each of the following questions.
- Each question carries 1 mark.
1. In which photosynthesis takes place?
A. Mitochondria
B. Chlorophyll
C. Arial roots
D. Middle Vein
Answer:
B. Chlorophyll
Explanation:
Photosynthesis takes place in chloroplasts in plant cells. The chlorophyll within the chloroplasts absorbs light energy, which is essential for photosynthesis. It captures sunlight and uses it to convert carbon dioxide and water into glucose and oxygen.
2. Number of ATP’s formed in glycolysis?
A. 2 ATP
B. 3 ATP
C. 6 ATP
D. 8 ATP
Answer:
A. 2 ATP
Explanation:
In the process of glycolysis, which occurs in the cytoplasm of the cell, 2 ATP molecules are produced per glucose molecule. Glycolysis is the first step of cellular respiration, where glucose is broken down into pyruvate, generating a net gain of 2 ATP molecules, despite the initial consumption of 2 ATP during the process.
3. How many excretory organs are there in the human body?
A. 110
B. 120
C. 150
D. 160
Answer:
B. 120
Explanation:
Humans have multiple excretory organs, including kidneys, lungs, skin, and liver. While the exact number can vary depending on classification, the main excretory organs that remove waste from the body include the kidneys (responsible for filtering blood and forming urine), the lungs (which excrete carbon dioxide), the skin (excreting sweat), and the liver (which helps detoxify substances and excretes bile).
4. What is the air sac-like structure in the lungs?
A. Alveoli
B. Air chambers
C. Bronchi
D. Bronchioles
Answer:
A. Alveoli
Explanation:
The alveoli are tiny, sac-like structures in the lungs where gas exchange occurs. Oxygen from the air passes through the walls of the alveoli into the bloodstream, while carbon dioxide from the blood moves into the alveoli to be exhaled. The alveoli increase the surface area for efficient gas exchange.
5. Which hormone promotes seedless fruits?
A. Auxins
B. Cytokinins
C. Abscisic acid
D. Gibberellins
Answer:
D. Gibberellins
Explanation:
Gibberellins are plant hormones that play a key role in promoting the growth and development of plants, including stimulating fruit growth. Specifically, gibberellins are used to induce parthenocarpy, the process of fruit development without fertilization, resulting in seedless fruits such as grapes and bananas.
6. What is the time between two cell divisions called?
A. Prophase
B. Telophase
C. Metaphase
D. Interphase
Answer:
D. Interphase
Explanation:
The time between two cell divisions is called interphase. It is the phase where the cell spends most of its life. Interphase includes three subphases: G1 (cell growth), S (DNA replication), and G2 (final preparations for division). This phase prepares the cell for division, ensuring it has enough resources and has replicated its DNA before mitosis or meiosis.
7. What is the best way to get plants with desired characters?
A. Hybridization
B. Grafting
C. Layering
D. Genetic modification
Answer:
D. Genetic modification
Explanation:
Genetic modification (GM) is the most effective way to obtain plants with desired characters. Through genetic engineering, scientists can directly alter a plant’s DNA to introduce beneficial traits, such as disease resistance, drought tolerance, or enhanced nutritional content. While hybridization, grafting, and layering are traditional methods, genetic modification offers more precision and efficiency in transferring specific traits.
8. Which alkaloid is used to treat malaria?
A. Quinine
B. Reserpine
C. Nimbin
D. Caffeine
Answer:
A. Quinine
Explanation:
Quinine is an alkaloid derived from the bark of the cinchona tree and has been used for centuries to treat malaria, a disease caused by the Plasmodium parasite transmitted through mosquito bites. Quinine acts by interfering with the parasite’s ability to metabolize hemoglobin, thus preventing the growth of the parasite.
9. Who introduced the principle of inheritance of acquired characteristics?
A. Darwin
B. Gregor Mendel
C. Lamarck
D. Morgan
Answer:
C. Lamarck
Explanation:
Jean-Baptiste Lamarck proposed the theory of the inheritance of acquired characteristics, which suggests that traits acquired by an organism during its lifetime can be passed on to its offspring. For example, Lamarck believed that giraffes developed long necks because their ancestors stretched their necks to reach higher leaves, and this trait was passed down. However, this idea was later replaced by Darwin’s theory of evolution and Mendelian genetics.
10. The phenotype ratio in dihybridization is?
A. 1:2:1
B. 9:3:3:1
C. 3:1
D. A & B
Answer:
B. 9:3:3:1
Explanation:
In a dihybrid cross, which involves two traits, the typical phenotypic ratio is 9:3:3:1. This ratio occurs when two organisms heterozygous for two traits are crossed (for example, AaBb x AaBb). It represents the distribution of different phenotypes based on the inheritance of two independent traits. The ratio indicates that there are:
- 9 individuals with both dominant traits,
- 3 individuals with one dominant and one recessive trait,
- 3 individuals with the other dominant and recessive trait,
- 1 individual with both recessive traits.