NEET Test 177

Asexual reproduction occurs usually in unicellular organisms in various ways like binary fission, budding,  sporulation, etc. In this method, a single parent produces offspring with or without the involvement of gametes.  Members of the kingdom fungi and simple plants reproduce through special asexual reproductive structures like conidia (Penicillium) buds (Hydra) etc. The most common of these structures are zoospores that are microscopic motile structures.  All other options are correct.

The name virus that means venom or poisonous fluid was given by Dmitri Ivanowsky (1892) recognized certain microbes as causal organisms of the mosaic disease of tobacco. These were found to be smaller than bacteria because they passed through bacteria-proof filters.

M.W. Beijerinek (1898) demonstrated that the extract of the infected plants of tobacco could cause infection in healthy plants and called the fluid Contagium vivum fluidum (infectious living fluid).

W.M. Stanley (1935) showed that viruses could be crystallized and crystals consist largely of proteins.

Planck’s quantum theory explains the emission and absorption of radiation. Postulates of Planck’s quantum theory are as follows:

(a) Different matter radiates energy or absorbs energy in discrete quantities discontinuously in the form of small bundles. These smallest bundles of energy can be emitted or absorbed in the form of electromagnetic radiation is known as quantum and in the presence of light, a quantum of light is known as a photon.

(b) The energy of the radiation absorbed or emitted is directly proportional to the frequency of the radiation.

(c) Energy less than quantum cannot be emitted or absorbed. A matter can radiate energy or absorb energy in the whole numbers which is a multiple of a quantum as nhv. Where n is a positive integer. So, the energy can be absorbed or radiate as hv, 2hv, 3hv, and so on; it can not be denoted as 1.5 hv, 2.5 hv, etc.

Tropical rain forests occur over equatorial or sub-equatorial regions with abundant warmth and rainfall (200-350 cms/ year) throughout the year. The forests are impenetrable with maximum diversity. Productivity is also maximum. Almost 200 different types of tall trees are expected in one hectare, which is maximum as compared to other forest types. Hence, most of the tree dwellers are expected in tropical rain forests.

For exothermic reaction ΔH = negative and if randomness increases it means ΔS becomes positive. Thus, according to ΔG = ΔH − TΔS, ΔG becomes negative so, the reaction is spontaneous.

Green and Purple photosynthetic organism is an anoxygenic photosynthetic organism. It works under the absence of light and takes part in light-independent reactions.

Anoxygenic photosynthesis is the phototrophic process where light energy is captured and converted to ATP, without the production of oxygen; water is, therefore, not used as an electron donor.

Purple sulfur bacteria (PSB) are photosynthetic and reduce carbon dioxide to carbohydrates using hydrogen sulfide instead of water. Green sulfur bacteria are strict anaerobes that are capable of photosynthesis. Green sulfur bacteria absorb longer wavelengths of light than purple sulfate bacteria.

Seat of origin of lateral root and formation of cork cambium are features related to Pericycle.

The pericycle is a heterogeneous, non-vascular tissue in plants that is divided into two populations — one at the xylem pole and one at the phloem pole. Pericycle cells at these poles are marked by differences in size, by ultrastructural features and by specific proteins and gene expression.