Biology Exam Answers
Section A
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1. Example of an interspecific hybrid is:
a) Tigon and ligerExplanation: A hybrid between two different species (e.g., lion and tiger) forms interspecific hybrids like ligers and tigons.
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2. The epithelial cells of Bowman’s capsule are called:
c) PodocytesExplanation: Podocytes are specialized epithelial cells in the Bowman’s capsule, important for filtration in the kidney.
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3. What is the name of heterocyclic carbon compound attached to sugar?
d) NucleosideExplanation: Nucleosides consist of a sugar molecule attached to a heterocyclic base.
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4. Monocotyledonous leaves are_________.
d) IsobilateralExplanation: Monocot leaves are isobilateral, meaning the structure of the leaf is symmetrical along both sides.
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5. In breathing movements, air volume can be estimated by:
b) SpirometerExplanation: A spirometer measures the volume of air inhaled and exhaled during breathing.
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6. Electrons from excited chlorophyll molecules of photosystem II to photosystem I transferred and finally convert:
c) ATP to NADHExplanation: During the light reactions of photosynthesis, ATP and NADPH are produced.
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7. Urea cycle operates in:
a) LiverExplanation: The urea cycle, responsible for converting ammonia to urea, occurs primarily in the liver.
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8. The number of nymphs produced from a single ootheca of the frog is _______.
b) 16Explanation: A frog’s ootheca usually produces about 16 nymphs.
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9. Phytochrome is sensitive to:
c) Red and far-red lightExplanation: Phytochrome is a plant pigment sensitive to red and far-red light, involved in regulating plant growth.
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10. In gymnosperms, cross-pollination is accompanied by-
d) WindExplanation: Gymnosperms typically rely on wind for cross-pollination.
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11. Diabetes insipidus is caused due to:
a) Reduced secretion of ADHExplanation: Diabetes insipidus results from a deficiency of antidiuretic hormone (ADH).
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12. How will you define the lungs?
a) Respiratory Control CentreExplanation: The lungs are part of the respiratory system, vital in gas exchange and regulation.
Section B
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1. Stomata are present on the ventral side of a dicot leaf. What may be the reason?
The stomata are usually on the lower side of leaves to reduce water loss by transpiration and prevent exposure to harsh sunlight.
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2. What is the difference between cutaneous and pulmonary respiration?
Cutaneous respiration: Involves gas exchange through the skin, as seen in amphibians.
Pulmonary respiration: Involves gas exchange through the lungs, as seen in mammals. -
3. Give example of Androgens and estrogens
Androgens: Testosterone
Estrogens: Estradiol -
4. Why is death considered a regulatory process on the earth?
Death helps in the recycling of organic matter and prevents overpopulation, ensuring ecological balance.
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5. A cyclic process is occurring in C3-plants, which is light-dependent and needs CO2. This process does not produce, but consumes energy. Can you name the given process?
The process is the Calvin cycle, part of photosynthesis in C3 plants, where CO2 is fixed and energy is consumed.
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6. Does moonlight support photosynthesis?
No, moonlight does not support photosynthesis as it is too weak and cannot be used by plants to synthesize food.
Section C
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1. Distinguish between Red, Brown, and Green Algae.
Red algae: Contain phycobilins and can live at greater depths.
Brown algae: Contain fucoxanthin, and are larger and often marine.
Green algae: Contain chlorophyll a and b, and are mostly freshwater. -
2. Endoparasites are found inside the host body. Mention the special structure, possessed by these and which enables them to survive in those conditions.
Endoparasites have specialized structures like hooks, suckers, or a tegument to protect them from the host’s immune system.
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3. List two properties of enzymes.
- Enzymes are highly specific in their action.
- Enzymes work optimally at a particular temperature and pH.
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4. Distinguish between Auxins and Gibberellins.
Auxins: Promote cell elongation, root formation.
Gibberellins: Stimulate growth and germination, increase stem elongation.
Section D
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1. Observed given table of Classification of Fungi and identify the class of fungi in which asexual spores are not found, vegetative reproduction occurs by fragmentation, and sexual organs are absent.
The class of fungi described is Deuteromycetes (Fungi Imperfecti).
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2. Where are Members of Phycomycetes found?
Members of Phycomycetes are found in aquatic habitats, on decaying wood in moist and damp places, or as obligate parasites on plants.
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3. What is Ascomycetes? What is the characteristic feature of Ascomycetes and Basidiomycetes?
Ascomycetes are sac fungi, typically multicellular, and produce asexual spores called conidia. They are characterized by the production of ascospores in an ascus.
Basidiomycetes are club fungi, typically producing basidiospores exogenously on a basidium. They include mushrooms, bracket fungi, and puffballs. -
OR: Identify the figure given below. Also, mention its characteristics.
[Insert image of fungal class]
The figure likely represents a type of fungi, such as a basidiomycete with basidia and basidiospores. -
4. What is the Androecium composed of?
The Androecium is composed of stamens, each consisting of a filament and an anther.
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5. The pollen grains are produced in pollen-sacs. What is a sterile stamen called?
A sterile stamen is called a staminode.
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6. Does Salvia and Mustard show variation in the length of filaments within a flower?
Yes, Salvia and Mustard show variation in the length of filaments. In Salvia, the filaments are often of unequal lengths, whereas in Mustard, the filaments are typically equal.
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OR: Mention statement justifies that the given figure is racemose inflorescence.
The statement that justifies this figure being a racemose inflorescence could be that the flower is arranged in a simple, unbranched manner, with the oldest flowers at the bottom and the youngest at the top.
Section E
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1. Mitosis results in producing two cells that are similar to each other. What would be the consequence if each of the following irregularities occur during mitosis?
a) Nuclear membrane fails to disintegrate: This would prevent the separation of chromosomes and hinder the progression of mitosis.
b) Duplication of DNA does not occur: This would result in unequal genetic material being distributed to the daughter cells.
c) Centromeres do not divide: Chromosomes would not be properly separated, leading to aneuploidy.
d) Cytokinesis does not occur: The cells would not physically divide, resulting in a multinucleate cell. -
OR: Explain, why a pair of homologous chromosomes is genetically different, but a pair of sister chromatids is genetically identical before crossing over in meiosis.
Homologous chromosomes are genetically different because they come from different parents and carry different alleles. Sister chromatids are genetically identical before crossing over because they are produced by the replication of the same chromosome during the S-phase of the cell cycle.
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2. Give an account of Glycolysis. Where does it occur? What is the end product? Trace the fate of these products in both aerobic and anaerobic respiration.
Glycolysis is the breakdown of glucose into pyruvate, producing a small amount of ATP and NADH. It occurs in the cytoplasm of the cell.
The end product is pyruvate. In aerobic respiration, pyruvate enters the mitochondria and undergoes further oxidation to produce more ATP. In anaerobic respiration, pyruvate is converted into lactic acid or ethanol, depending on the organism. -
OR: Where is the electron transport system operative in mitochondria? Explain the system highlighting the role of oxygen.
The electron transport system operates in the inner mitochondrial membrane. In this system, electrons are transferred through a series of protein complexes and ultimately combine with oxygen to form water, producing a proton gradient that drives ATP synthesis through oxidative phosphorylation.
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3. The cells of a unicellular organism are usually spherical whereas those of multicellular tend to be many-sided. Why?
The shape of unicellular organisms is spherical because it allows for a smaller surface area to volume ratio, making it more efficient for exchange of materials. Multicellular organisms have specialized cells that form various shapes to perform different functions and maintain structural integrity.
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OR: What is the difference between the cell wall and ribosomes of a prokaryotic and a eukaryotic cell?
In prokaryotic cells, the cell wall is made of peptidoglycan, and ribosomes are smaller (70S). In eukaryotic cells, the cell wall (if present) is made of cellulose (plants) or chitin (fungi), and ribosomes are larger (80S).