Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

Photosynthesis in C4 plants is relatively less limited by atmospheric CO2 levels because

  • there is effective pumping of CO2 into bundle sheath cells

  • RuBisCO in C4 plants has higher affinity for CO2

  • six carbon acids are the primary initial CO2 fixation products

  • the primary fixation of CO2 is mediated via PEP carboxylase.


D.

the primary fixation of CO2 is mediated via PEP carboxylase.

CO2 acceptor molecule in C4 plants is phosphoenol pyruvate (PEP). C4 plants are more efficient in picking up CO2 even when it is found in low concentration because of high affinity of PEP. PEP carboxylase (PEPcase) is the key enzyme which catalyses the primary fixation of CO2.


12.

The chemiosmotic coupling hypothesis of oxidative phosphorylation proposes that adenosine triphosphate (ATP) is formed because

  • a proton gradient forms across the inner mitochondrial membrane

  • there is a change in the permeability of the inner mitochondrial membrane towards adenosine diphosphate (ADP).

  • high energy bonds are formed in mitochondrial proteins

  • ADP is pumped out of the matrix into the intermembrane space


A.

a proton gradient forms across the inner mitochondrial membrane

The chemiosmotic hypothesis was given by Mitchell. It explains the process of ATP formation and states that it is linked to development of proton gradient across the mitochondrial membrane. ATP synthase is required for ATP synthesis is located in F1 particles. It becomes active only when there is high concentration of proton on F0 side as compared to F1 side. 


13.

A plasmolysed cell can be deplasmolysed by placing it in

  • isotonic solution

  • saturated solution

  • pure water or hypotonic solution

  • hypertonic solution


C.

pure water or hypotonic solution

Hypotonic Solution is the solution in which the concentration of solutes is greater inside the cell than outside of it.

Hypertonic Solution is the solution where the concentration of solutes is greater outside the cell than inside it.

Isotonic Solution refers to two solutions having the same osmotic pressure across a semi- permeable membrane.

Saturated Solution is a chemical solution containing the maximum concentration of a solute dissolved in the solvent.


14.

Assertion : Gap junctions perform cementing function to keep the neighbouring cells together.

Reason : Tight junctions facilitate the cells to communicate with each other by connecting the cytoplasm of adjoining cells, for rapid transfer of ions, small and big molecules, etc.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false

  • If both assertion and reason are false


D.

If both assertion and reason are false

Gap junctions are direct cytoplasm to cytoplasm connections between many kinds of animal cells, these are meant for chemical exchange between cells. Whereas tight junctions are the regions where membranes of adjacent animal cells are held close together by sealing strands. They lie cells firmly and check movement of materials between them.


15.

Assertion : Consciousness is considered as the defining property of living organisms.

Reason : All organisms, from the prokaryotes to the most complex eukaryotes can sense and respond to environmental stimuli.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


A.

If both assertion and reason are true and reason is the correct explanation of assertion.

Consciousness is awareness of the surroundings and responding to external stimuli. The external stimuli can be physical, chemical or biological. All organisms, from primitive prokaryotes to most advanced and complex eukaryotes, are able to sense and respond to environmental factors. Consciousness is thus said to be the defining property ofliving organisms.


16.

Yeast is not included in protozoans but in fungi because

  • it has chlorophyll

  • it shows saprotrophic mode of nutrition

  • it has eukaryotic organisation

  • cell wall is made up of cellulose and reserve food material as starch


B.

it shows saprotrophic mode of nutrition

Saprotrophic mode of nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of dead or decayed organic matter. The palnts which exhibit saprotrophic mode of nutrition are known as saprotrophs. Saprotroph organism is an organism which gets its energy from dead and decaying organic matter. 


17.

Which of the following is a group of micronutrients for plants?

  • Fe, Mn, Cu, Mo, Zn

  • Fe, Mn, Cu, O, C

  • Cu, B, Cl, Fe, Ca

  • Ca, Mg, Fe


A.

Fe, Mn, Cu, Mo, Zn

Micronutrients or trace elements are needed in very small amounts (less than 10 m mole kg-1 of dry matter). These are 8 in number and include Iron (Fe), Manganese (Mn), Copper (Cu), Molybdenum (Mo), Zinc (Zn), Boron (B), Chlorine (Cl) and Nickel (Ni).


18.

Which one of the following is correct for the transmembrane proteins in lipid bilayer of plasma membrane?

  • They are absent in animal cells

  • They act as channel proteins

  • They are absent in plant cells

  • They are only externally located


B.

They act as channel proteins

The tunnel proteins or transmembrane proteins run throughout the lipid bilayer and individually or in group form channels for the passage of water and water soluble substances. The channels however, possess selective properties for passage of different ions and other polar substances.


19.

As secondary growth proceeds, in a dicot stem, the thickness of

  • sapwood increases

  • heartwood increases

  • both sapwood and heartwood increases

  • both sapwood and heartwood remains the same


B.

heartwood increases

In a woody stem, due to secondary growth, secondary xylem constitutes the bulk of the stem and is commonly called wood. Width of secondary xylem increases continuously with the age of the plant. 

Older stem have two regions- younger sapwood and older heartwood. Both sapwood and heartwood increase in size initially, but when a tree reaches a certain age, amount of heartwood increases and the amount of sapwood remains constant.


20.

Identify the labelled part in the given figure and select the correct option.

  • A - Heterocyst, B - Mucilaginous sheath

  • A - Mucilaginous sheath, B - Heterocyst

  • A - Heterocyst, B - Capsid

  • A - Pseudopodia, B - Mucilaginous sheath


A.

A - Heterocyst, B - Mucilaginous sheath

Heterocysts are specialized nitrogen fixing cells formed during nitrogen starvation by some filamentous cyanobacteria, such as Nostoc punctiforme etc.

Mucilaginous sheath of blue- green algae is to bind colonies together and to permit movement.