Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

Which one of the following is not a microelement for plants?

  • Cu

  • B

  • Zn

  • Cr


D.

Cr

Plants require many organic and inorganic nutrients to complete their life-cycle. It has been established that some elements are required by plants in relatively large amount and are called major elements or macronutrients, e.g., Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Sulphur (S), Phosphorus (P), Potassium (K), Calcium (Ca) and Magnesium (Mg).

Microelements or minor elements or trace elements are required by plants in very small amount, less than 1 ppm. eg. Iron (Fe), Copper (Cu), Boron (B), Zinc (Zn), Manganese (Mn), Molybdenum (Mo), Chlorine (Cl). Thus Chromium (Cr) is not a microelement.


12.

The branched sclereids present in hydrophytes are

  • osteosclereids

  • trichosclereids

  • macrosclereids

  • astrosclereids


D.

astrosclereids

Sclereids are highly thickened dead sclerenchyma cells with very narrow cavities. They may also be branched. They provide stiffness to the parts in which they occur. It is of many types : brachysclereids, macrosclereids, osteosclereids, astrosclereids, trichosclereids and filiform sclereids.

Astrosclereids are star-shaped, having various branches or arms. They are found in intercellular spaces of leaves and stems of many hydrophytes like Nymphaea.

Osteosclereid is the sclereid forming the hypodermal layer in many fruits and seeds. It also occurs in the leaves of certain xerophytes.

Trichosclereids are hard needle like branched cells found in some species of plants that serve the purpose of protecting the plant from herbivores.

Macrosclereid is one of the columnar sclereids that often form an outer layer in various fruits and seeds and also occur in the stems of some plants.


13.

Which of the following sugars is not plants?

  • sucrose

  • glucose

  • lactose

  • fructose


C.

lactose

Sucrose, Glucose and Fructose are found in plants. Sucrose is the commercial sugar which is obtained from sugarcane. Glucose is the main respiratory substrate in plants and animals. Fructose is commonly known as fruiting sugar. Lactose or milk sugar is found in sugar. It is the reducing sugar which is formed in the mammary glands of mammals through condensation of two hexose molecules.


14.

The outermost limiting layer of mycoplasma is made up of

  • cell wall

  • cell membrane

  • mucilaginous sheath

  • slime layer


B.

cell membrane

Mycoplasma are the smallest and simplest free living Gram Negative Prokaryotes or Monerans. In these, cell wall is absent. Plasma Membrane forms the outer boundary of the cell. A substantial amount of polysaccharides having acetyl glucosamine are associated with cell membrane.


15.

Which of the following is true?

  • Umbel is a racemose inflorescence where all stalked flower aggregate on the flat receptacle

  • Raceme is a racemose inflorescence having main axis shortened & flower born acropetally

  • Spadix is a racemose inflorescence having pendulous spike with main axis much flattened.

  • Spike is a racemose inflorescence having sessile flowers


D.

Spike is a racemose inflorescence having sessile flowers

Spike is a racemose inflorescence that bears sessile flowers in an acropetal fashion, e.g., chaff flower (Achyranthes), bottle brush (Callistemon), Adathoda vasica, Amaranthus.


16.

Bark refers to

  • phellem + phellogen + phelloderm

  • periderm + cortex

  • phellem + phelloderm + secondary phloem

  • periderm + cortex + pericycle + secondary phloem


D.

periderm + cortex + pericycle + secondary phloem

Bark is a loose term and is used to define all the tissues outside vascular cambium. It is the outermost layer of stems and roots of woody plants. It is further differentiated into outer bark or rhytidome (consisting of dead cells) and inner bark (of living cells, i.e., periderm, cortex, pericycle and secondary phloem). The outer layer of the bark are being constantly peeled off on account of the formation of new secondary vascular tissues in the interior. Bark is insect repellent, decay proof, fire-proof and acts as a heat screen.


17.

The enzyme decarboxylase catalyses the following step

  • conversion of citric acid to cis aconitic acid

  • fumaric acid to malic acid

  • oxalosuccinic acid to α- ketoglutaric acid

  • malic acid to oxaloacetic acid


C.

oxalosuccinic acid to α- ketoglutaric acid

Oxalosuccinate is decarboxylated to form α- ketoglutarate through the enzyme decarboxylase. It is one of the step involved in Krebs' cycle. It releases one molecule of CO2.

Oxalosuccinate Mg2+Decarboxylase α- ketoglutarate + CO2


18.

Which of the following statements about Spirogyra is correct?

  • Lateral conjugation takes place in homothallic species

  • Scalariform conjugation takes place in homothallic species.

  • Lateral conjugation takes place in heterothallic species

  • The type of conjugation is unrelated to homothallic and heterothallic species


A.

Lateral conjugation takes place in homothallic species

Sexual reproduction in Spirogyra takes place by the process of conjugation. In Spirogyra, the process of conjugation may be of two types -

  1. Scalariform Conjugation:- It occurs in heterothallic species.
  2. Lateral Conjugation:- It occurs between the adjacent cells of the same filament of homothallic species of Spirogyra. It is of two types- Indirect Lateral Conjugation or Direct Lateral Conjugation.


19.

Jute fibres deteriorate quickly because

  • cellulose content is high

  • lignin content is high

  • cellulose content is low

  • lignin content is low


B.

lignin content is high

Lignin is a complex organic polymer that is deposited within the cellulose of plant cells. The lignin content is high in jute fibres which causes deterioration very quickly.


20.

Which ofthe following is true regarding the given electron transport chain?

CoQ Cyt c Cyt aa3 O2

  • CoQ Cyt c is H+ absorbing site

  • aa3 O2, Hyielding site

  • CoQ Cyt c is Hyielding site and aa3 O2 is H+ absorbing site

  • No H+ is absorbed or released


C.

CoQ Cyt c is Hyielding site and aa3 O2 is H+ absorbing site

In electron transport chain electrons transport through a series of carriers. H+ of NADH+ (received from Kreb' s cycle) is accepted by FAD as a result of which FAD is reduced to FADH+ and NADH+ is oxidised to NAD. Reduced FADH+ is oxidised by CoQ with the formation of CoQH+. H+ ions then move to Cyt b, then Cyt c, Cyt a and Cyt aa3. Ultimately these H+ are acceped by O2 and H2O is formed.