NEET Biology Cell Biology Plant Kingdom and Plant Physiology MCQs Set 01

Answer: (c) Pteridophytes : non-vascular cryptogams

Explanation:
1. Pteridophytes are the first terrestrial plants with vascular tissues (xylem and phloem), so they are vascular cryptogams, not non-vascular ones.
2. The other three matches are correct: algal sex organs are unicellular and jacketless, a bryophyte sporophyte depends on the gametophyte, and the gymnosperm endosperm (female gametophyte) forms before fertilisation.

Teacher's Note:
1. Cryptogams are plants with hidden reproductive organs, and they include algae, bryophytes and pteridophytes.
2. Only bryophytes among them lack vascular tissue (non-vascular).

Answer: (c) Viruses are made up of either DNA or RNA and proteins.

Explanation:
1. A virus has one kind of nucleic acid, either DNA or RNA, enclosed in a protein coat (capsid).
2. Lichens are very good pollution indicators because they do not grow in polluted air, viroids are much smaller than viruses (free RNA only), and the potato spindle tuber disease is caused by a viroid, not a prion.

Teacher's Note:
1. Viroids have only RNA and no protein coat.
2. Prions are infectious proteins that cause diseases such as mad cow disease.

Answer: (a) two different species but both belong to the same genus

Explanation:
1. Potato is \(\textit{Solanum tuberosum}\) and brinjal is \(\textit{Solanum melongena}\).
2. They share the genus \(\textit{Solanum}\) but have different species names, so they are two different species of the same genus.

Teacher's Note:
1. In a binomial name the first word is the genus and the second is the species epithet.
2. Same genus implies the same family.

Answer: (a) 6

Explanation:
1. Independent, free-living gametophytes are found in bryophytes and pteridophytes.
2. Sphagnum, Equisetum, Polytrichum, Funaria, Adiantum and Marchantia are 6 such examples.
3. In gymnosperms (Cedrus, Ginkgo, Pinus, Cycas) the gametophyte is dependent on the sporophyte.

Teacher's Note:
1. In gymnosperms and angiosperms the gametophyte is highly reduced and retained on the sporophyte.
2. In bryophytes the gametophyte is the dominant phase.

Answer: (b) Solanaceae

Explanation:
1. Solanaceae have bisexual, actinomorphic flowers with a bicarpellary, obliquely placed syncarpous ovary and a swollen placenta bearing many ovules.
2. Liliaceae have a tricarpellary ovary, Fabaceae have a monocarpellary ovary, and Cruciferae have a bicarpellary ovary with a replum and a false septum.

Teacher's Note:
1. Potato, tomato, brinjal and tobacco belong to Solanaceae.
2. The fruit is a berry or a capsule.

Answer: (a) Liliaceae

Explanation:
1. \(\textit{Gloriosa}\) (glory lily), \(\textit{Asparagus}\), \(\textit{Allium}\) and \(\textit{Aloe}\) are monocots of the family Liliaceae.

Teacher's Note:
1. Liliaceae flowers are trimerous with six tepals.
2. Many members are used as ornamentals, vegetables and medicinal plants.

Answer: (b) monocot root

Explanation:
1. Monocot roots are polyarch, with usually more than six xylem bundles, and the xylem is exarch.
2. Dicot roots usually have two to four (diarch to tetrarch) xylem bundles, and stems have endarch xylem.

Teacher's Note:
1. Roots have exarch xylem and stems have endarch xylem.
2. Monocot roots also have a large pith.

Answer: (b) zygotene

Explanation:
1. Prophase I has five substages. In zygotene homologous chromosomes pair up in a process called synapsis, forming the synaptonemal complex.
2. Crossing over takes place later in pachytene, and chiasmata become visible in diplotene.

Teacher's Note:
1. The order is leptotene, zygotene, pachytene, diplotene, diakinesis.
2. The paired chromosomes at zygotene are called bivalents or tetrads.

Answer: (b) 0.2 to 1.0 \(\mu\)m

Explanation:
1. Mitochondria are sausage-shaped or cylindrical with a diameter of 0.2 to 1.0 \(\mu\)m (average 0.5 \(\mu\)m) and a length of 1.0 to 4.1 \(\mu\)m.

Teacher's Note:
1. Note that 1 to 4.1 micrometres is the length, not the diameter.
2. These values are easy to confuse in the NCERT text.

Answer: (c) in animals it occupies about 90% of the volume of the cell

Explanation:
1. The vacuole is bound by a single membrane called the tonoplast, is part of the endomembrane system, and contains water, sap and excretory products.
2. In plant cells the vacuole can occupy up to 90% of the cell volume. In animal cells vacuoles are small, so statement (c) is incorrect.

Teacher's Note:
1. The tonoplast regulates the movement of ions into the vacuole.
2. Contractile and food vacuoles are the animal examples.

Answer: (c) Robert Brown discovered the cell.

Explanation:
1. Robert Hooke discovered the cell in 1665 by examining cork slices. Robert Brown discovered the nucleus in 1831.
2. So (c) is incorrect. The other three statements are correct.

Teacher's Note:
1. Leeuwenhoek was the first to see a living cell.
2. Schleiden and Schwann formulated the cell theory, and Virchow added that new cells arise from pre-existing cells.

Answer: (c) sucrose

Explanation:
1. Sucrose is made of \(\alpha\)-D-glucose and \(\beta\)-D-fructose.
2. Maltose is two glucose units and lactose is glucose plus galactose. Glycogen is a polysaccharide, not a disaccharide.

Teacher's Note:
1. Sucrose is a non-reducing sugar because both anomeric carbons are involved in the bond.
2. Invertase hydrolyses sucrose into glucose and fructose.

Answer: (b) glycogen

Explanation:
1. The bond joining monosaccharides in glycogen is an O-glycosidic bond (\(\ce{C-O-C}\)).
2. Nucleic acids join the sugar and base through an N-glycosidic bond, and nucleotides are joined by phosphodiester bonds. Lecithin has ester bonds, and ribose is a monosaccharide with no glycosidic bond.

Teacher's Note:
1. A glycosidic bond joins the anomeric carbon of a sugar to another group.
2. The name of the bond depends on the atom it is linked to (O or N).

Answer: (c) fructose

Explanation:
1. Fructose has six carbons and a ketone group at C-2, so it is a ketohexose.
2. Glucose is an aldohexose, and ribose and arabinose are aldopentoses.

Teacher's Note:
1. Ketoses end with the suffix -ulose in the systematic naming.
2. Fructose is the sweetest naturally occurring sugar.

Answer: (d) repressor

Explanation:
1. The \(i\) gene (inhibitor gene) codes for the repressor protein, which binds the operator and blocks transcription in the absence of the inducer.
2. The structural genes \(z\), \(y\) and \(a\) code for \(\beta\)-galactosidase, permease and transacetylase.

Teacher's Note:
1. Lactose (allolactose) is the inducer that binds the repressor and frees the operator.
2. The \(i\) gene is expressed continuously (constitutively).

Answer: (c) an obligatory and transient formation

Explanation:
1. The substrate must bind the active site for the reaction to take place, so ES complex formation is obligatory.
2. The complex breaks down to give the product and the free enzyme, so it is only transient.

Teacher's Note:
1. The enzyme is regenerated unchanged at the end of the reaction.
2. Transient means that it lasts only for a short time.

Answer: (d) active absorption of minerals by the root

Explanation:
1. Transpiration cools the leaf, supplies water for photosynthesis and carries the minerals in the xylem sap upward with the transpiration pull.
2. Absorption of minerals by roots is largely active and needs energy. It is not a function of transpiration.

Teacher's Note:
1. Transpiration pull is the main force for the ascent of sap in tall trees.
2. Mineral uptake depends on ATP in the root cells.

Answer: (c) death of tissues

Explanation:
1. Necrosis is the death of tissue, usually in the leaf tips and margins.
2. Loss of chlorophyll is chlorosis, and inhibition of cell division and delayed flowering are other deficiency symptoms.

Teacher's Note:
1. Chlorosis and necrosis are the two main deficiency symptoms.
2. Ca, Mg, Cu and K deficiencies all show necrosis.

Answer: (d) Jan Ingenhousz with his experiment on an aquatic plant

Explanation:
1. Jan Ingenhousz showed, using an aquatic plant (\(\textit{Hydrilla}\)) in a transparent jar, that sunlight is essential and that only the green parts of the plant release oxygen.
2. Priestley showed that plants restore air, Engelmann described the action spectrum, and van Niel showed that oxygen comes from water.

Teacher's Note:
1. Priestley discovered the role of plants in restoring air, but not the need for sunlight.
2. Engelmann used the alga \(\textit{Cladophora}\) and aerobic bacteria.

Answer: (c) A = 9.45 kcal/g, B = 9.0 kcal/g

Explanation:
1. The gross calorific value of fat is 9.45 kcal/g and the physiological value (energy available to the body) is 9.0 kcal/g.
2. Carbohydrates give 4.1 kcal/g (gross) and 4.0 kcal/g (physiological), and proteins give 5.65 and 4.0 kcal/g.

Teacher's Note:
1. Physiological value is slightly lower than gross because digestion and absorption are not 100 percent efficient.
2. Fat gives more than twice the energy of carbohydrate per gram.

Answer: (c) cytokinin

Explanation:
1. Auxin from the apical bud suppresses the growth of the lateral (axillary) buds.
2. Cytokinins promote the growth of lateral buds, so they oppose the effect of auxin and are antagonistic to it in apical dominance.

Teacher's Note:
1. Removing the apical bud (decapitation) releases the lateral buds, so hedges are pruned.
2. Cytokinins also delay senescence and promote cytokinesis.

Answer: (b) psilophytons

Explanation:
1. Psilophytons (the early vascular plants such as \(\textit{Rhynia}\)) were the ancestors of the ferns, and through progymnosperms the conifers arose from them.

Teacher's Note:
1. Psilophytes are extinct early land plants and Psilotum is a living relative.
2. Bryophytes are a separate side branch and did not give rise to vascular plants.