Which structure in plant cells is analogous to the centrosome in animal cells?

The correct answer is B: Plasmodesmata. While plant cells lack true centrosomes with centrioles, plasmodesmata serve similar intercellular communication functions. However, most plant cells lack a distinct MTOC (microtubule-organizing center).

Which of the following is a hydrophobic protein complex involved in photosynthesis?

The correct answer is B: Photosystem I (PSI) in thylakoid membrane. Photosystem I is an integral membrane protein complex with multiple transmembrane domains, making it hydrophobic. Rubisco is soluble, while ferredoxin and plastocyanin are soluble electron carriers. This biochemical distinction is important for understanding photosynthetic mechanisms.

What is the equivalent resistance when three resistors of 6Ω, 3Ω, and 2Ω are connected in parallel?

The correct answer is A: 1Ω. For parallel connection: 1/R = 1/6 + 1/3 + 1/2 = 1/6 + 2/6 + 3/6 = 6/6 = 1. Therefore R = 1Ω.

Newton first law also called?

The correct answer is C: Law of inertia. First law = Law of Inertia.

A body falls freely from rest. What is its velocity after 2 seconds? (g = 10 m/s²)

The correct answer is B: 20 m/s. Using v = u + gt, where u = 0 (at rest), t = 2s, g = 10 m/s². Therefore v = 0 + 10 × 2 = 20 m/s.

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37 Q 8 Topics Take Mock Test

Difficulty: All Easy Medium Hard 31–37 of 37

Topics in General Science

All Physics 106 Chemistry 9 Biology 2 Botany 78 Human Body 4 Disease & Health 2 Space & Astronomy 5 Environment 1

Q.31 Hard Botany

The double fertilization process in angiosperms results in the formation of:

A Seed coat and cotyledon

B Endosperm and embryo

C Fruit and seed

D Ovule and nucellus

Correct Answer: B. Endosperm and embryo

EXPLANATION

Double fertilization: one sperm fuses with egg nucleus (embryo), other fuses with polar nuclei (endosperm - 3n).

Test

Q.32 Hard Botany

When a plant wilts despite adequate soil moisture, this condition is called:

A Permanent wilting point

B Incipient wilting

C Physiological wilting

D Hydration stress

Correct Answer: C. Physiological wilting

EXPLANATION

Physiological wilting occurs when transpiration rate exceeds water absorption rate, though soil moisture is sufficient.

Test

Q.33 Hard Botany

In the nitrogen cycle, the conversion of atmospheric N2 into ammonia is carried out by:

A Nitrosomonas

B Rhizobium

C Nitrobacter

D Thiobacillus

Correct Answer: B. Rhizobium

EXPLANATION

Rhizobium bacteria in root nodules of legumes fix atmospheric nitrogen into ammonia through nitrogenase enzyme.

Test

Q.34 Hard Botany

The pulling force that moves water upward in xylem vessels is primarily due to:

A Root pressure alone

B Capillary action alone

C Transpirational pull (tension) in xylem

D Gravitational force

Correct Answer: C. Transpirational pull (tension) in xylem

EXPLANATION

Cohesion-tension theory explains that water is pulled upward due to transpirational pull creating negative pressure in xylem.

Test

Q.35 Hard Space & Astronomy Space Science

Which of the following statements about the Oort Cloud is incorrect?

A It is a theoretical spherical shell of icy bodies surrounding our solar system

B It extends approximately 100,000 to 200,000 AU from the Sun

C It is the primary source of long-period comets

D It has been directly observed through telescopes and contains approximately 1 trillion objects

Correct Answer: D. It has been directly observed through telescopes and contains approximately 1 trillion objects

EXPLANATION

The Oort Cloud remains theoretical and has never been directly observed; we infer its existence from comet trajectories and orbital studies.

While estimates suggest it contains billions to trillions of icy bodies, these objects are too distant and too small to be directly observed with current technology, making option D the incorrect statement among the given choices.

Test

Q.36 Hard Chemistry

Which of the following substances will have the lowest lattice enthalpy among ionic compounds?

A NaCl

B MgO

C CsI

D CaF₂

Correct Answer: C. CsI

EXPLANATION

Lattice enthalpy depends inversely on ionic radius and directly on ionic charge.

CsI has the lowest lattice enthalpy (~604 kJ/mol) because both Cs⁺ and I⁻ are large ions with 1+ and 1- charges respectively.

In contrast, MgO has very high lattice enthalpy due to small, highly charged ions (Mg²⁺ and O²⁻), while NaCl and CaF₂ have intermediate values.

Test

Q.37 Hard Chemistry

Which of the following compounds exhibits both ionic and covalent bonding characteristics and is commonly used in coordination chemistry?

A Sodium chloride

B Potassium hexacyanoferrate(III)

C Carbon dioxide

D Calcium oxide

Correct Answer: B. Potassium hexacyanoferrate(III)

EXPLANATION

Potassium hexacyanoferrate(III) contains both ionic bonds (between K⁺ and the [Fe(CN)₆]³⁻ complex) and covalent bonds (between Fe and CN ligands, and within the CN groups).

This complex salt is extensively used in coordination chemistry and analytical procedures like the Prussian blue test.

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