NEET SECTION - A [BOTANY - MCQ]

(D)
Ligaments are dense regular connective tissue that connect bone to bone. Cartilage is one of the types of specialised connective tissues.

(D)
Flatworms (e.g., Taenia) have excretory systems called protonephridia with flame cells.
Freshwater Paramoecium have osmoregulatory organelle called contractile vacuole. Urecose glands in Cockroaches (Periplaneta) helps in excretion. In earthworms (Pheretima), the excretory organs are nephridia.

(D)
Radial symmetry: When any plane passing through the central axis of the body divides the organism into two identical halves.
Bilateral symmetry: When the body can be divided into identical left and right halves in only one plane.
The adult echinoderms are radially symmetrical but larvae are bilaterally symmetrical.
Coelenterates and Ctenophores are radially symmetrical animals.
Hemichordates are bilaterally symmetrical animals.

(C)
Mutualism: This interaction confers benefits on both the interacting species.
Commensalism: This is the interaction in which one species benefit (+) and other in neutral (o).
Amensalism: In this interaction one species is harmed (-) whereas the other in unaffected (o).
Parasitism: In this interaction one species benefit (+) and other is harmed (-).

(A)
Gause's 'Competitive Exclusion Principle' states that two closely related species competing for the same resources cannot co-exist indefinitely and the competitively inferior one will be eliminated eventually. In general, herbivores and plants appear to be more adversely affected by competition than carnivores.

(D)
Main steps in the formation of recombinant DNA in correct sequence are:
B: Cutting of DNA at specific location by restriction enzyme.
C: Isolation of desired DNA fragment by electrophoresis.
D: Amplification of gene of interest using PCR.
A: Insertion of recombinant DNA into the host cell.

(C)
The cellular factory responsible for synthesising proteins is the ribosome. The ribosome consists of structural RNAs and about 80 different proteins.

(D)
Klinefelter's Syndrome is a genetic disorder that also caused due to the presence of an additional copy of X chromosome resulting into a karyotype of 47, XXY. Such an individual has overall masculine development, however, the feminine development (development of breast, i.e., Gynaecomastia) is also expressed. Such individuals are sterile.
Down syndrome was first described by Langdon down (1866). In this disorder affected individual is physically, psychomotorly and mentally retarded.

A

(D)
Chemiosmosis requires a membrane, a proton pump, a proton gradient and ATP synthase. Energy is used to pump protons across a membrane, to create a gradient or a high concentration of protons within the thylakoid lumen. ATP synthase has a channel that allows diffusion of protons back across the membrane; this releases enough energy to activate ATP synthase enzyme that catalyses the formation of ATP.

(B)
The competitive inhibitor competes with the substrate for the substrate binding site of the enzyme. Consequently, the substrate cannot bind and as a result, the enzyme action declines, e.g. inhibition of succinic dehydrogenase by malonate which closely resembles the substrate succinate in structure. Such competitive inhibitors are ofter used in the control of bacterial pathogens.

(B)
Polysiphonia, Porphyra, Gracilaria and Gelidium are examples of red algae. Ectocarpus, Dictyota, Laminaria, Sargassum and Fucus are examples of brown algae.

(C)
A flower is a modified shoot wherein the shoot apical meristem changes to floral meristem. Internodes do not elongate and the axis gets condensed. The apex produces different kinds of floral appendages laterally at successive nodes instead of leaves.

(C)
In gymnosperms, the pollen grain is released from the microsporangium. They are carried in air currents and come in contact with the opening of the ovules borne on megasporophylls. The pollen tube carrying the male gametes grows towards archegonia in the ovules and discharge their contents near the mouth of the archegonia.

(D)
There are four major causes of biodiversity losses (The Evil Quartet) that are habitat loss and fragmentation, overexploitation, Alien species invasion and co-extinctions. Habitat loss and fragmentation is the most important cause driving animals and plants to extinction.

(D)
The historic Convention on Biological Diversity ('The Earth Summit') held in Rio de Janeiro in 1992, called upon all nations to take appropriate measures for conservation of biodiversity and sustainable utilisation of its benefits.

(C)
Gross primary productivity minus respiration losses (R), is the net primary productivity (NPP)

(A)
Detritus food chain (DFC) begins with detritus or dead organic matter. Detrivores (eg. Earthworm, millipeds, slugs) perform fragmentation process on dead decaying material in any ecosystem. Humus a dark nutrient rich substance is degraded by microorganisms releasing inorganic nutrients into the soil. This process is known as mineralization. By the process leaching, water soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts.

(C)
Addition of chilled ethanol precipitates the genomic DNA during the isolation of DNA or genetic material.

(A)
A biolistic or gene gun is a technique of genetic engineering where the genes, DNA, RNA or proteins are transferred to the plant cells without the use of any vectors. The genetic material is coated with heavy metal i.e. gold or tungsten bombarded with the heavy velocity.

(D)
In gel electrophoresis the separated DNA fragments can be visualized only after staining the DNA with a compound known as ethidium bromide followed by exposure to UV radiation. Bright orange coloured bands of DNA can be seen when stained with ethidium bromide and exposed to UV light.

(C)
The unequivocal proof that DNA is the genetic material came from the experiments of Alfred Hershey and Martha Chase (1952). They worked with viruse that inject bacteria called bacteriophages.

(B)
All the genes that are expressed as RNA are referred to as Expressed sequence Tags (EST) are focussed on identifying all the genes that are expressed as RNA.

(B)
In eukaryotes, The RNA polymerase I transcribes rRNAs (28S, 18S, and 5.8S), whereas the RNA polymerase III is responsible for transcription of tRNA, 5srRNA, and snRNAs (small nuclear RNAs). The RNA polymerase II transcribes precursor of mRNA, the heterogeneous nuclear RNA (hnRNA)

B

(D)
Generally effect of a gene can be seen on a single phenotype of a trait. However, there are instances where a single gene can exhibit multiple phenotype expression. Such a gene is called a pleiotropic gene.

(B)
Wind pollinated flower eg. Zea mays (maize) have nonessential whorls such as calyx, corolla, bracts and bracteoles are not showy. Flowers are devoid of scent and nectar. The tessels represent the stigma and style. Pollen grains are dry, very small sized, non-sticky and unwettable, so that they can be carried by wind to the long distances. Stigma is hairy, feathery that catches the wind borne pollens.

(B)
In angiosperms, the haploid diploid and triploid structure of a fertilised embryo sac sequentially are- Synergids, Zygote and Primary endosperm nucleus

(C)
Majority of insect-pollinated flowers are large, colorful, fragrant flowers and rich in nectar. These characteristics off were attract insect and thus help in pollination.

B

(C)
The living differentiated cells, that by now have lost the capacity to divide can regain the capacity of division under certain conditions. This phenomenon is termed as dedifferentiation. Same occurs in tissue culture of leaf.

(D)
Spraying of gibberellins on juvenile conifers, hastens the maturity period and thus leading to early seed production.

(D)
ATP is utilised at two steps: first in the conversion of glucose into glucose 6-phosphate and second in the conversion of fructose 6-phosphate to fructose 1, 6-bisphosphate.

(A)
The first two stages of prophase I are relatively shortlived compared to the next stage that is pachytene. During this stage the four chromatids of each bivalent chromosomes became distinct and clearly appears as tetrads. This stage is characterized by the appearance of recombination nodules, the site at which crossing over occurs between non-sister chromatids of the homologous chromosomes.

(B)
Anaphase stage is characterised by the following key events:
1. Centromeres split and chromatids separate.
2. Chromatids move to opposite poles.

(D)
In eukaryotes, S or Synthesis phase marks the period during which DNA synthesis or replication takes place. During this phase the amount of DNA per cell doubles.

(B)
Potato and brinjal are two different species but both belong to the genus Solanum. Lion (Panthera leo), leopard (P. pardus) and tiger (P. tigris) with several common features, are all species of the genus Panthera. This genus differs from another genus Felis which includes cats.

Common Name	Biological Name	Genus	Family	Order	Class	Phylum/Division
Man	Homo sapiens	Homo	Hominidae	Primata	Mammalia	Chordata
Housefly	Musca cdomestica	Musca	Muscidae	Diptera	Insecta	Arthropoda
Mango	Mangifera indica	Mangifera	Anacardiaccac	Sapindales	Dicotyledonne	Angiospermac
Wheat	Triticum aestivum	Triticum	Poaceae	Poales	Monocotyledonne	Angiospermae

(D)
In roots, the protoxylem lies towards periphery and metaxylem lies towards the centre. Such arrangement of primary xylem is called exarch. Endarch and exarch xylem are the terms used for primary xylem.

(B)
In axile placentation ovules are attached to multilocular ovary as in china rose, petunia and lemon.

(B)
Genera like Selaginella and Salvinia which produce two kinds of spores, macro (large) and micro (small) spores, are known as heterosporous.

(D)
Mosses spores released from the capsule germinate to form the filamentous structure called protonema. It is the first stage of gametophyte.