SRMJEEE Biology Mock Test - 7 - JEE MCQ

Mitosis is the type of cell division that ensures equal distribution of genetic material in daughter cells. Mitosis can occur both in diploid and haploid cells.
The main function of mitosis is to make copies of cells for growth and regeneration.

• The polymerase chain reaction is a technology in molecular biology used to amplify a single copy or a few copies of a piece of DNA.
• Calcium ions is not required in PCR technology.

At prophase I, DNA replication has already occurred, and the original amount of DNA has been doubled to x. At anaphase I, the amount of DNA in the cell remains the same because no cytokinesis has occurred yet to separate the cytoplasm.

Ribozymes are RNA molecules that have catalytic activity, meaning they can catalyze reactions like protein enzymes.

In plants, cytokinesis or division of cytoplasm occurs due to the formation of the cell plate.

In animals, cytokinesis occurs due to the formation of constriction in the middle cell membrane.

Filtration occurs through 3 layers: the endothelium of blood capillaries, the basement membrane of the epithelium and the filtration slits of the renal capsule. The endothelium ofblood capillaries contains large pores which donot filter out larger molecules, The basement membrane consists of a meshwork of collagen fibres that are able to filter them out. The filtration silts are formed by the podocytes and do not hinder the passage of large molecules.

Soil bacterium, Bacillus thuringiensis (Bt) produces proteins that kill certain insects like lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes). Bacillus thuringiensis forms some intracellular protein crystals. These crystals contain a toxic insecticidal protein. The Bt toxin protein exists as inactive toxin and is converted into an active form due to the alkaline pH of the alimentary canal that solubilises the crystals. The activated toxin binds to the surface of midgut epithelial cells and create pores which cause cell swelling and lysis and finally cause death of the insect.

The chlorophyll pigments which are excited give up their electrons and to compensate for the loss of electrons, water is split to release four H⁺ ions and four electrons and O². The electrons that are lost from the PSII enter into an electron transfer chain or ETC.

When the external intercostal muscles and diaphragm relax, the ribs move downward and inward and diaphragm becomes convex (dome shaped), thus decreasing the volume of thoracic cavity and increasing the pressure inside as compared to the atmospheric pressure outside. This will cause the air to move out (expiration).

Genetic engineering involves:
(i) Identifying DNA with desirable genes.
(ii) Introduction of identified DNA into the host.
(iii) Maintenance of introduced DNA in the host.
(iv) Transfer of DNA in its progeny.

Hence, option C is correct.

The algae groups are correctly matched with their distinct characteristics as follows:

• 1-B (Chlorophyceae - Green Algae): Characterized by chlorophyll a and b, cell walls made of cellulose and pectose, and reproduces asexually by flagellated zoospores.
• 2-A (Phaeophyceae - Brown Algae): Noted for being found primarily in marine habitats, contains chlorophyll a and c, and stores food as complex carbohydrates like laminarin or mannitol.
• 3-C (Rhodophyceae - Red Algae): Known for being predominantly in warmer marine areas, stores food as floridean starch, and reproduces sexually by non-motile gametes which are oogamous.

Thus, Option A is the correct answer providing the precise matching of algae groups with their respective characteristics.

Xenogamy is the cross-pollination between the flowers of different plants. Cross pollination is the transfer of pollen grains from the anther of one flower to the stigma of a genetically different flower. Cross pollination is performed with the help of an external agency.

Amphibians are particularly vulnerable to extinction due to their sensitive skin, environmental requirements, and the impact of habitat loss, climate change, and diseases.

The original statement that neurons regulate endocrine activity is not entirely correct. Both the nervous system and the endocrine system interact with and regulate each other.

• The nervous system can influence endocrine glands through nerves, such as the hypothalamus controlling the pituitary gland.
• Conversely, hormones produced by endocrine glands can affect neural activity, demonstrating a two-way interaction.

Therefore, the idea that only one system regulates the other is inaccurate. The correct statement reflects the mutual regulation between these systems.

In agarose gel electrophoresis, the DNA fragments separate out (resolve) according to their size or length because of the sieving property of agarose gel. It means, the smaller the fragment size, the farther it will move.

A centriole is a barrel - shaped cell structure found in most animal eukaryotic cells, though absent in higher plants and most fungi.

Bt toxin gene has been closed from the bacteria and expressed in plants to provide resistance to insects without the need for insecticides. Examples are Bt cotton, Bt corn, rice, tomato, potato and soybean, etc.

Autogamy (Gk. autos-self, gamos-marriage) is a type of self-pollination in which an intersexual or perfect flower is pollinated by its own pollen.

Geitonogamy is a type of pollination in which pollen grains of one flower are transferred to the stigma of another flower belonging to either the same plant or a genetically similar plant. In geitonogamy, the flowers often show modifications similar to ones found in xenogamy or cross-pollination.

Xenogamy or cross-pollination is the transfer of pollen grains from the anther of one flower to the stigma of a genetically different flower.

Based on the number of axon and dendrites, the neurons are divided into three types, i.e., multipolar (with one axon and two or more dendrites; found in the cerebral cortex), bipolar (with one axon and one dendrite, found in the retina of eye) and unipolar (cell body with one axon only; found usually in the embryonic stage).

• The arteries carry blood from the heart to all over body parts. Hence, statement (i) is correct.
• The vessels which carry blood from the heart to the lungs is the pulmonary artery but it carries deoxygenated blood. Hence, statement (ii) is correct.

(A) Cellular level
(B) Radial symmetry
(C) Bilateral symmetry
(D) Pseudocoelomates
(E) Coelomates

The globular head of a meromyosin molecule functions as an active ATPase enzyme. This enzyme has specific binding sites for ATP and actin, playing a crucial role in muscle contraction by enabling the interaction of myosin with actin filaments, thereby converting chemical energy into mechanical energy.
 

RNA polymerase synthesizes RNA in the 5' → 3' direction and follows the template-strand direction. In prokaryotes, translation can begin while mRNA is still being transcribed.

They are generally marine and mostly asymmetrical animals . These are primitive multicellular animals and have cellular level of organisation. Sponges have a water transport or canal system. Water enters through minute pores (ostia) in the body wall into a central cavity, spongocoel, from where it goes out through the osculum. This pathway of water transport is helpful in food gathering, respiratory exchange and removal of waste. Choanocytes or collar cells line the spongocoel and the canals. Digestion is intracellular. The body is supported by a skeleton made up of spicules or spongin fibres. Sexes are not separate (hermaphrodite), i.e., eggs and sperms are produced by the same individual. Sponges reproduce asexually by fragmentation and sexually by formation of gametes. Fertilisation is internal and development is indirect having a larval stage which is morphologically distinct from the adult.

The development of the male gametophyte in angiosperms is called as microgametogenesis. Pollen grain is the first cell of a male gametophyte. This cell undergoes only two divisions, with the result of first division two cells are formed - a large vegetative cell and a small generative cell. The second division is concerned with generative cell only. This division may take place either in pollen grain or in the pollen tube and gives rise to two male gametes.

The exine is the outer layer of the pollen grain and is known for its diverse patterns and designs. These patterns are key for identification and fertilization.

The middle lamella serves as a cementing layer between the primary walls of adjacent cells.
The primary wall is the cellulose-containing layer laid down by cells that are dividing and growing. 

Photophosphorylation is the process in which ATP is produced, which is called as energy currency of the cell. During this process, ADP is phosphorylated to give ATP in presence of light energy.
So, the correct answer is option B.

Condensation of DNA molecules begins in prophase.

• The process of RNA and protein synthesis occurs during interphase.
• Cytoplasmic growth also takes place in this phase.
• However, the polymerisation of spindle fibres and the disappearance of Golgi bodies and endoplasmic reticulum (ER) do not happen until later stages of the cell cycle.
• During interphase, DNA remains in a less condensed state, unlike its highly supercoiled form seen in prophase.

There are 2,70,000 species of higher plants and 72,000 species of fungi and in the world.