Q. 1. (A) Choose the correct option and write the correct alternative.
(i) A molecule of glucose is completely oxidised in aerobic respiration and molecules of \(H_{2}O\) and __________ are produced along with energy.
Answer: (A) \(CO_{2}\)
(ii) Vinegar contains __________ acid.
Answer: (A) acetic
(iii) Any nucleotide of the gene suddenly changes its position that causes a minor change which is nothing but the __________.
Answer: (B) mutation
(iv) In humans, sperm production occurs in the __________ organ.
Answer: (C) testes
(v) Solar photovoltaic cell converts the solar radiation energy directly into __________ energy.
Answer: (D) Electrical
Q. 1. (B) Answer the following questions.
(i) Find the odd one out: Fragmentation, Regeneration, Budding, Fertilization.
Answer: Fertilization
Reason: Fertilization involves sexual reproduction, while Fragmentation, Regeneration, and Budding are types of asexual reproduction.
Reason: Fertilization involves sexual reproduction, while Fragmentation, Regeneration, and Budding are types of asexual reproduction.
(ii) Write the correct co-relation: Diabetes : Insulin :: Cancer : _______
Answer: Interferon (or Chemotherapy)
(iii) State whether true or false: Study of fossils is an important aspect of the study of evolution.
Answer: True
(iv) Give any two commercial uses of Biotechnology.
Answer:
- Production of vaccines and antibiotics.
- Production of genetically modified crops (e.g., Bt Cotton).
- Production of yogurt and other dairy products.
(v) Being a fish, I perform respiration with the help of lungs. Who am I?
Answer: Lungfish
Q. 2. (A) Give scientific reasons (any two).
(i) Sometimes, higher plants and animals too perform anaerobic respiration.
Reason:
- Aerobic respiration requires oxygen. However, when the oxygen level in the surroundings is depleted, higher plants and animals switch to anaerobic respiration to survive.
- For example, during heavy exercise, human muscle cells perform anaerobic respiration due to a lack of oxygen, producing lactic acid.
- Similarly, plants may perform anaerobic respiration if the soil is waterlogged and roots cannot access oxygen.
(ii) It is not right to consider the mother responsible for giving birth to a girl child.
Reason:
- Human females have two X chromosomes (XX), so all egg cells produced carry an X chromosome.
- Human males have one X and one Y chromosome (XY). Therefore, 50% of sperms carry the X chromosome and 50% carry the Y chromosome.
- The sex of the child depends entirely on which sperm fertilizes the egg. If an X-bearing sperm fertilizes the egg, the child is a girl (XX). If a Y-bearing sperm fertilizes the egg, the child is a boy (XY). Thus, the father determines the sex of the child.
(iii) The energy generated from nuclear fuels is not environment friendly.
Reason:
- Nuclear power plants produce radioactive waste which is hazardous and difficult to dispose of safely.
- There is a risk of harmful radiation leakage which can cause severe health problems, including cancer and genetic mutations.
- Accidents in nuclear plants can lead to catastrophic environmental disasters.
Q. 2. (B) Answer the following questions (any three).
(i) Complete the following food chain: Grass -> ______ -> Frog -> ______ -> Eagle -> ______
Answer:
Grass -> Grasshopper -> Frog -> Snake -> Eagle -> Fungi
Grass -> Grasshopper -> Frog -> Snake -> Eagle -> Fungi
(ii) Distinguish between Class Pisces and Class Reptilia (Reptiles).
| Class Pisces | Class Reptilia |
|---|---|
| They are aquatic animals (live in water). | They are mostly terrestrial (live on land) and creep/crawl. |
| Respiration occurs through gills. | Respiration occurs through lungs. |
| Body is covered with scales. | Skin is dry and rough with scales/scutes. |
(iii) Observe the picture (Train in flood water) and write any two effects of this disaster.
Note: The image depicts a flood situation.
Effects of Floods:
- Disruption of life: Transportation systems (like trains) collapse, and daily life comes to a standstill.
- Economic Loss: Huge loss of life and property; damage to crops and infrastructure.
- Health Hazards: Spread of water-borne diseases and contamination of drinking water sources.
(iv) Write any four methods to reduce stress.
Answer:
- Regular Exercise and Yoga.
- Meditation.
- Pursuing hobbies like reading, painting, or singing.
- Communication with parents and friends (Socializing).
(v) Complete the following conceptual picture: Sewage after processing.
Answer: The by-products obtained after sewage processing are:
Potable Water / Clean Water
Biogas (Fuel)
Sludge (Fertilizer/Manure)
Electricity (from Biogas)
Q. 3. Answer the following questions (any five).
(i) Define heredity. Explain the mechanism of hereditary changes.
Definition: Heredity is the transfer of biological characters from one generation to another via genes.
Mechanism of Hereditary Changes:
Mechanism of Hereditary Changes:
- Mutation: Sometimes, any nucleotide of the gene changes its position, causing a minor change in the genetic code. This is called mutation.
- Recombination: During meiosis (gamete formation), crossing over occurs between homologous chromosomes, leading to genetic variation.
- These changes can lead to evolution and the development of new species over long periods.
(ii) Write any four stages of mitosis and explain any two of them.
The four stages of Mitosis (Karyokinesis) are:
1. Prophase 2. Metaphase 3. Anaphase 4. Telophase.
Explanation:
Explanation:
- Prophase: Chromosomes condense and become visible. The nuclear membrane and nucleolus start to disappear. Centrioles move to opposite poles.
- Metaphase: Chromosomes align parallel to the equatorial plane (center) of the cell. Spindle fibers attach to the centromere of each chromosome.
(iii) Explain with examples types of asexual reproduction in unicellular organism.
Types of Asexual Reproduction in Unicellular Organisms:
- Binary Fission: The parent cell divides into two equal daughter cells. Example: Amoeba, Paramecium.
- Multiple Fission: Under unfavorable conditions, the parent creates a cyst and divides many times inside to produce multiple daughter cells. Example: Amoeba.
- Budding: A small outgrowth (bud) forms on the parent cell, grows, and eventually detaches to form a new organism. Example: Yeast.
(iv) Which fuel is used in thermal power plant? Write any two problems associated with this type of power generation.
Fuel Used: Coal.
Problems:
Problems:
- Air Pollution: Burning coal releases harmful gases like Carbon Dioxide (\(CO_2\)), Sulphur Dioxide (\(SO_2\)), and Nitrogen Oxide (\(NO_x\)) which cause respiratory issues and acid rain.
- Soot Particles: Minute soot particles released into the air can cause serious health problems related to the respiratory system.
(v) Write three characteristics of phylum-Mollusca.
Characteristics of Phylum Mollusca:
- Body Structure: They have a soft, slimy body. They are the second-largest phylum in the animal kingdom.
- Shell: Most molluscs have a hard, calcareous shell which provides protection. It may be external or internal.
- Locomotion: They move with the help of a muscular foot.
- Habitat: They are aquatic (marine or fresh water) or terrestrial. (Example: Snail, Octopus, Bivalve).
(vi) What are the constituents of acid rain? What are its two effects on earth's surface?
Constituents: Sulphuric acid (\(H_2SO_4\)) and Nitric acid (\(HNO_3\)). These are formed when oxides of sulphur and nitrogen react with rain water.
Effects:
Effects:
- Soil and Water Bodies: Acidity of soil and water bodies increases, harming aquatic life and plants.
- Damage to Structures: Acid rain causes corrosion of buildings, bridges, historical monuments (like the Taj Mahal), and metal structures.
(vii) Solve the following crossword (Based on Social Health).
Clues & Answers:
- 1. (Across) Continuous consumption of alcoholic and tobacco materials: ADDICTION
- 2. (Down) This app may cause cyber crimes (6 letters, crosses 'C'): SOCIAL (Referring to Social Media) or MOBILE.
- 3. (Down) A remedy to resolve stress (Crosses 'N'): FRIEND (Spending time with friends reduces stress) or SINGING.
- 4. (Down) Requirement for stress free life (Crosses 'D'): GARDEN (Hobbies) or INDOOR (Games).
(viii) Write down the reasons, effects and remedial measures taken for any one disaster seen or heard by you.
Example Disaster: Earthquake
- Reasons: Movement of tectonic plates inside the earth's crust, volcanic eruptions, or mining activities.
- Effects: Collapse of buildings, loss of life, landslides, disruption of electricity and communication lines.
- Remedial Measures:
- Take cover under a strong table or door frame.
- Move to open ground away from buildings.
- Help victims and call emergency services.
Q. 4. Answer the following questions (any one).
(i) What is biodiversity? Write any four steps to conserve biodiversity.
Biodiversity: It is the richness of living organisms in nature due to the presence of varieties of organisms, ecosystems, and genetic variations within a species.
Steps to Conserve Biodiversity:
Steps to Conserve Biodiversity:
- Protecting rare species of organisms.
- Establishing National Parks and Sanctuaries.
- Declaring some regions as "Bio-reserves".
- Projects for conservation of special species.
- Observing the rules regarding the ban on poaching/hunting.
(ii) What is stem cell? Write any four uses of stem cell.
Stem Cell: Stem cells are special types of undifferentiated cells in multicellular organisms that have the ability to differentiate into various types of specialized cells (like muscle cells, blood cells, etc.).
Uses of Stem Cells:
Uses of Stem Cells:
- Regenerative Therapy: Used in Cell Therapy to replace dead cells in diseases like Diabetes and Alzheimer's.
- Organ Transplantation: Used to produce organs like the liver or kidney for patients in need.
- Blood Cell Production: To treat blood diseases like Thalassemia and Leukemia.
- Research: Used to study the development of diseases and test new drugs.
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