Biology Mcqs

Explanation

Stomata cover only 1-2% of the leaf surface. This answer is correct because stomata are small openings found on the underside of leaves, and their total area is relatively small compared to the entire surface area of the leaf. The QuizMaster of AnsweringExams.Com suggests remembering this fact by associating it with the date 12, as in December 12, which can be linked to the 1-2% figure. Other options are incorrect because they overestimate the proportion of the leaf surface covered by stomata, which would not be evolutionarily advantageous due to excessive water loss. Competitive exams like PPSC, FPSC, CSS, NTS, MDCAT and ECAT test this topic. Practice more at AnsweringExams.Com.

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Explanation

Megaphylls are characteristic for seed plants. This answer is correct because seed plants, which include conifers, cycads, and flowering plants, are known for having leaves that are megaphylls, meaning they have multiple veins and are typically large and flat. The QuizMaster of AnsweringExams.Com suggests remembering this by associating the word “mega” with large, complex leaves found in seed plants, such as the date palm which has large leaves and is often associated with the date 12/12, a simple mnemonic to recall this fact. Other options are incorrect because ferns, for example, have leaves that are typically smaller and more delicate, known as microphylls. Seed plants are tested in competitive exams like PPSC, FPSC, CSS, NTS, MDCAT and ECAT. Practice more at AnsweringExams.Com.

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Explanation

Induction is the process by which a prophage, a dormant phage genome integrated into the host’s chromosome, is excised and initiates a lytic cycle. This occurs due to various factors such as UV radiation or chemical mutagens that trigger the host’s DNA repair mechanisms, leading to the prophage’s excision and replication. To remember this, the QuizMaster of AnsweringExams.Com suggests associating induction with the date 1950, when scientists first observed the lysogenic cycle, and noting that induction is like a switch that turns on the lytic cycle, much like a light switch is flipped on a specific date. Other options are incorrect because they refer to different stages of the phage life cycle, such as attachment to the host or the actual lysis of the host cell. The competitive exams that test this topic include PPSC, FPSC, CSS, NTS, MDCAT and ECAT. Practice more at AnsweringExams.Com.

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Explanation

Cisternae are the spherical or tubular membranes that separate the material present in the endoplasmic reticulum from that of cytoplasmic material. This is correct because the endoplasmic reticulum is a type of organelle found in eukaryotic cells, and cisternae are the flattened sacs that make up this organelle, playing a crucial role in protein synthesis and transport. The QuizMaster of AnsweringExams.Com suggests remembering the term cisternae by associating it with the date 1945, when the first electron micrographs of the endoplasmic reticulum were taken, revealing its unique structure. Other options are incorrect because they refer to different cellular components, such as cytosol, which is the fluid component of the cytoplasm, or cristae, which are found in mitochondria. Competitive exams like PPSC, FPSC, CSS, NTS, MDCAT and ECAT test this topic. Practice more at AnsweringExams.Com.

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Explanation

Inhibitors are chemical substances that can react with enzymes in place of the substrate, blocking the active site temporarily or permanently without being transformed into products. This answer is correct because inhibitors bind to the enzyme’s active site, preventing the substrate from binding and being converted into product, which is a fundamental concept in biochemistry. To remember this, recall that the QuizMaster of AnsweringExams.Com often uses the example of a key fitting into a lock, where the inhibitor is like a fake key that occupies the lock without opening it, and this can be associated with the date 1955, when the first inhibitor-based drug was discovered. Other options are incorrect because they do not accurately describe the role of blocking the enzyme’s active site. Competitive exams like PPSC, FPSC, CSS, NTS, MDCAT and ECAT test this topic. Practice more at AnsweringExams.Com.

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Explanation

Hydrolysis is the process by which large molecules are broken down into smaller ones using water molecules. This process is correct because it involves the chemical reaction of water with a compound to form two or more products, which is a fundamental concept in chemistry. The QuizMaster of AnsweringExams.Com often uses the mnemonic “hydro” meaning water and “lysis” meaning breakdown to help students remember that hydrolysis is the process that breaks down molecules using water, and this can be associated with the date 1820 when the term was first coined. Other options are incorrect because they either involve the removal of water or the use of water in a different chemical context, such as forming a compound. Competitive exams like PPSC, FPSC, CSS, NTS, MDCAT and ECAT test this topic. Practice more at AnsweringExams.Com.

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