NEET Practice Questions (MCQs) with Answers & Solutions

Protista kingdom was created by Haeckel (1886). It includes all unicellular and colonial eukaryotes except those of green and red algae. Protists were the first eukaryotes to evolve about 1000 million years back. They are mostly aquatic. They are broadly divided into three groups - photosynthetic, slime moulds and protozoans. Photosynthetic protists are photoautotrophic like diatoms, dinoflagellates and euglenoids. Protozoan protists include sarcodines/amoebae, zooflagellates, sporozoans and ciliates. It does not include bacteria. Bacteria are simple prokaryotes, occurring in soil, water and air and as symbionts, parasites and pathogens of animals, plants and other micro-organisms.

Lichens represent an unique example of mutualism between algae and fungi. In these plants algae (phycobionts ) and fungi (mycobionts) live together in such a way that they appear as one organism. On the basis of type of thallus the lichens are divided into three type–

(i) Crustose or crustaceous: They occur as thin or thick crust over rocks, soil, tree barks etc.

(ii) Foliose or foliaceous: These are leaf like lichens, which attach to the substratum by means of special rhizoid like organs developed from lower side of thallus.

(iii) Fruticose or filamentous: Cylindrical, flat or ribbon like, branched structures attached to the substratum by their basal ends. They are shrubby lichens.

The fruiting bodies of Agaricus are also known as basidiocarp. They are present above the soil and edible in young stage.

Phycology is the study of algae. Algae are photosynthetic organisms that range from unicellular to multicellular forms. They lack true roots, stems, and leaves, and reproduce through spores or gametes.

None of the groups i.e., algae, fungi or mosses are purely anaerobic. Algae- The group algae includes most primitive plants with simple thalloid body. They are chlorophyll bearing photosynthetic aerobes.

Fungi- Generally aerobic but some unicellular forms like yeast can respire anaerobically (fermentation) which are beneficial and used in many industries for production of various products such as alcohol, enzymes, bread, etc.

Mosse- Includes simplest and primitive land plants which occupy a position between algae and pteridophyta.

A virus is a small particle that infects cells in biological organisms. Viruses are obligate intracellular parasites; they can reproduce only by invading and taking over othe cells as they lack the cellular machinery for self reproduction.

Viral envelope is a loose membranous covering that occurs in some animal viruses, rarely plant and bacterial viruses. In contrast to enveloped viruses, the viruses without an envelope are called naked. Envelope consists of proteins from (virus), lipids and carbohydrates (from host). It has subunits called peplomeres. Surface of envelope can be smooth or have outgrowths called spikes. Common enveloped viruses are HIV, herpes virus, vaccinia virus, etc.

Hepatitis B virus (HBV) is a DNA-containing double-shelled virus. It belongs to the Hepadnaviridae family and is a major cause of chronic liver disease and hepatocellular carcinoma worldwide.

In prokaryotes, chromatophores are internal membrane systems that may become extensive and complex in photosynthetic bacteria. They contain pigments like chlorophyll and carotenoids, and are involved in photosynthesis.

Under continuous supply of food and space in the laboratory conditions the bacterial population grows exponentially and shows a J-shaped curve, thus the curve would be hyperbolic.

Such populations ultimately crash when the population size grows beyond carrying capacity.

Tobacco mosaic virus (TMV) is a single-stranded RNA virus that infects plants, especially tobacco and other members of the family Solanaceae. Its genetic material is a single-stranded, positive-sense RNA molecule.