Biology

251. After fertilization, the fruit and the seed are produced by

After fertilization, the fruit and the seed are produced by

[amp_mcq option1=”ovule and ovary, respectively” option2=”ovary and ovule, respectively” option3=”ovary, no ovule required” option4=”ovule, no ovary required” correct=”option2″]

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The correct answer is B) ovary and ovule, respectively.
After fertilization in flowering plants, the ovary, which contains the ovules, develops and matures into the fruit. Simultaneously, the ovules inside the ovary develop and mature into seeds. Therefore, the fruit is produced by the ovary, and the seed is produced by the ovule.
The process of fertilization is the fusion of the male gamete (from the pollen) with the female gamete (egg cell) inside the ovule. This triggers the development of the embryo within the ovule and the maturation of the ovule into a seed and the ovary into a fruit. The fruit serves to protect the seed and aid in its dispersal.

252. The digestive enzymes are present in

The digestive enzymes are present in

[amp_mcq option1=”mitochondria” option2=”vacuoles” option3=”lysosomes” option4=”ribosomes” correct=”option3″]

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The correct answer is lysosomes.
Lysosomes are membrane-bound organelles within eukaryotic cells that contain a variety of hydrolytic enzymes, often referred to as digestive enzymes. These enzymes function best in an acidic environment (pH ~4.5-5.0) and are responsible for breaking down waste materials, cellular debris, and pathogens within the cell through processes like autophagy and phagocytosis.
Mitochondria are responsible for cellular respiration and energy production. Vacuoles in animal cells are typically small and involved in storage or transport. Ribosomes are the sites of protein synthesis.

253. Which one of the following will be resulted when an animal cell is sur

Which one of the following will be resulted when an animal cell is surrounded by a medium with lower concentration of water?

[amp_mcq option1=”Cell will lose water” option2=”No change in movement of water” option3=”Cell will gain water” option4=”Cell will swell up” correct=”option1″]

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The correct answer is Cell will lose water.
Osmosis is the movement of water across a semi-permeable membrane from a region of higher water potential (lower solute concentration) to a region of lower water potential (higher solute concentration). A medium with a “lower concentration of water” means it has a higher concentration of solutes compared to the cell’s cytoplasm; such a medium is hypertonic to the cell. Therefore, water will move by osmosis from inside the cell (higher water concentration) to the surrounding medium (lower water concentration).
If the medium had a *higher* concentration of water (lower solute concentration, hypotonic), the cell would gain water and swell. If the medium had the *same* concentration of water (isotonic), there would be no net movement of water. In a hypertonic solution, animal cells lose water and crenate (shrink).

254. The protein-digesting enzyme secreted by the stomach wall in case of m

The protein-digesting enzyme secreted by the stomach wall in case of mammals is called

[amp_mcq option1=”chitinase” option2=”amylase” option3=”pepsin” option4=”trypsin” correct=”option3″]

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The correct answer is pepsin.
The stomach lining secretes gastric juice containing hydrochloric acid and enzymes. The primary protein-digesting enzyme in the stomach is pepsin. Pepsin is secreted in an inactive precursor form called pepsinogen, which is converted to active pepsin by the acidic environment created by hydrochloric acid.
Amylase (e.g., salivary amylase) digests carbohydrates. Trypsin is a protein-digesting enzyme secreted by the pancreas and active in the small intestine. Chitinase digests chitin, a polysaccharide found in the exoskeletons of insects and fungi.

255. The breakdown of glucose in cytoplasm results in the formation of

The breakdown of glucose in cytoplasm results in the formation of

[amp_mcq option1=”pyruvate and energy” option2=”pyruvate and carbon dioxide” option3=”pyruvate and oxygen” option4=”pyruvate and nitrogen” correct=”option1″]

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The breakdown of glucose begins in the cytoplasm through a process called glycolysis. Glycolysis breaks down one molecule of glucose into two molecules of pyruvate. This process also produces a small amount of ATP, which is a form of energy for the cell.
Glycolysis occurs in the cytoplasm and converts glucose into pyruvate, yielding energy (ATP).
Carbon dioxide is released during the subsequent stages of cellular respiration (Krebs cycle and oxidative phosphorylation) if oxygen is present, which occur in the mitochondria. Oxygen is consumed during oxidative phosphorylation. Nitrogen is not directly involved in the breakdown of glucose for energy production.

256. Lymph is a tissue fluid present in intercellular spaces. It resembles

Lymph is a tissue fluid present in intercellular spaces. It resembles to

[amp_mcq option1=”digestive juice” option2=”cytoplasmic fluid” option3=”urine” option4=”plasma” correct=”option4″]

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Lymph is essentially tissue fluid that has entered the lymphatic vessels. Tissue fluid is formed from blood plasma that filters out of capillaries into the interstitial spaces. Therefore, lymph has a composition similar to plasma, but it contains fewer proteins and no red blood cells (though it contains white blood cells).
Lymph is derived from interstitial fluid, which is derived from blood plasma. Hence, lymph resembles plasma in its general composition, minus most proteins and red blood cells.
Digestive juice contains enzymes for digestion. Cytoplasmic fluid is the material within a cell, outside the nucleus. Urine is a waste product filtered by the kidneys. Plasma is the liquid component of blood.

257. Which one of the following statements about animal cells and plant cel

Which one of the following statements about animal cells and plant cells is correct?

[amp_mcq option1=”Animal cells have only cell membrane not cell wall, whereas plant cells have only cell wall not cell membrane.” option2=”Animal cells have only cell membrane not cell wall, but plant cells have both.” option3=”Both animal and plant cells have cell membrane and cell wall.” option4=”Only some cells of animals have cell wall and all plant cells have cell membrane.” correct=”option2″]

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Animal cells are surrounded only by a cell membrane. Plant cells have both a cell membrane and a rigid cell wall located outside the cell membrane.
The presence of a cell wall is a defining characteristic of plant cells (and fungal, algal, and bacterial cells) that is absent in animal cells. Both plant and animal cells have a cell membrane.
The cell membrane regulates the passage of substances into and out of the cell and is present in all known cell types. The plant cell wall provides structural support, protects the cell, and prevents excessive water uptake.

258. The digestion of fat in human intestine is performed by

The digestion of fat in human intestine is performed by

[amp_mcq option1=”trypsin” option2=”bile and lipase” option3=”bile and amylase” option4=”bile and pepsin” correct=”option2″]

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The digestion of fat in the human intestine is primarily performed by enzymes called lipases, which break down fats into fatty acids and glycerol. Bile, produced by the liver and stored in the gallbladder, is released into the intestine to emulsify large fat globules into smaller droplets. This emulsification increases the surface area available for lipase action, making the digestion more efficient.
Fat digestion requires both the emulsifying action of bile and the enzymatic action of lipase.
Trypsin and pepsin are enzymes that digest proteins. Amylase is an enzyme that digests carbohydrates (starch). Without bile, the digestion of fats by lipase would be very slow and incomplete due to the large size of fat globules. The major fat-digesting enzyme in the intestine is pancreatic lipase.

259. Which one of the following hormones increases the heartbeat in

Which one of the following hormones increases the heartbeat in mammals?

[amp_mcq option1=”Insulin” option2=”Melatonin” option3=”Thyroxine” option4=”Adrenaline” correct=”option4″]

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Adrenaline is the hormone that increases the heartbeat in mammals.
Adrenaline (also known as epinephrine) is a hormone produced by the adrenal medulla. It is released in response to stress and triggers the “fight or flight” response. One of its key effects is to increase heart rate and force of contraction, leading to increased blood pressure and cardiac output.
Insulin lowers blood glucose. Melatonin regulates sleep cycles. Thyroxine increases metabolic rate, which indirectly affects heart rate over time, but adrenaline causes a rapid increase in heart rate in response to acute stimuli.

260. Human eye can see objects at different distances with contrasting illu

Human eye can see objects at different distances with contrasting illuminations. This is due to

[amp_mcq option1=”far-sightedness” option2=”near-sightedness” option3=”far-sightedness and near-sightedness” option4=”accommodation of eye” correct=”option4″]

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Human eye can see objects at different distances with contrasting illuminations due to the accommodation of eye.
The ability of the eye to adjust its focal length to see objects clearly at different distances is called accommodation. This is achieved by changing the shape of the lens. While “contrasting illuminations” involves other mechanisms like pupil size adjustment (controlled by the iris) and adaptation of photoreceptor cells, “accommodation of eye” is the term that best describes the eye’s overall ability to adjust to different viewing conditions presented in the question, especially the “different distances” aspect, and is the only adaptive mechanism listed among the options.
Far-sightedness and near-sightedness are refractive errors, not adaptive mechanisms. Accommodation primarily refers to focusing for distance, but in a broader sense, the eye’s overall ability to adapt to changing viewing conditions (distance and light) is a form of accommodation or adaptation. Given the options, “accommodation of eye” is the most appropriate answer describing the dynamic adjustment process.
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