CPMT Botany - 2008

Basidiocarp is the fruiting body of basidiomycetes that produces the basidia. It is the edible part in a mushroom.

This is the characteristic of angiosperms, and not gymnosperms. Here, the xylem is made up of xylem parenchyma, tracheids and fibres only.

Photochemical smog is haze in the atmosphere that is accompanied by high levels of ozone and nitrogen oxides. It is caused by the action of sunlight on pollutants.

There are two forms of polyembryony with respect to the origin of the embryos: simple, due to the fertilisation of several eggs and cleavage, and due to the splitting of products of zygote. This is common in pinus.

Binomial system of classification is the system of nomenclature in which two terms are used to denote a species of living organism, the first one indicating the genus and the second the specific epithet. This was given by Linnaeus.

The opening of stomata occurs due to the influx of K⁺ ions into the guard cells. The source of K⁺ ions are the neighbouring subsidiary and epidermal cells. It increases the concentration from 50 mM to 300 mM in guard cells. The increase in K⁺ ion concentration increases the osmotic concentration of guard cells. It leads to stomatal opening. ATP helps in entry of K⁺ ions into the guard cells.

The Avena geo-curvature test is a bioassay for auxin-type growth regulators. Much of our current knowledge of auxin was obtained from its applications.

Indusium is a thin membrane covering the sorus of a fern. It often shrivels away when spores are ready to be dispersed.

The cohesion of water explains only maintenance of the sap column. The explanation for the upward movement of the water is accounted for by a mechanism, called transpiration pull, that involves the evaporation of water from leaves. It is the most accepted theory for ascent of sap.

Transposable elements (TEs), also known as jumping genes or transposons, are sequences of DNA that move (or jump) from one location in the genome to another. Maize geneticist Barbara McClintock discovered TEs in 1940s and for decades thereafter, most scientists dismissed transposons as useless or junk DNA.

Each microsporophyll has two attached microsporangia. Microsporangia are organs that contain microsporocytes (immature pollen grains).

The biological species concept defines a species as members of population that actually or potentially interbreed in nature, not according to similarity of appearance. The mechanisms of reproductive isolation or hybridisation barriers are a collection of mechanisms, behaviours and physiological processes that prevent the members of two different species that cross or mate from producing offspring or which ensure that any offspring that may be produced are sterile.

In plants, adhesion forces water up the columns of cells in the xylem.

Duramen is the name given by botanists to the central wood or heart wood in a tree trunk.

Phanerogams are flowering or seed-bearing plants. They are the most advanced plants. They possess well-developed roots, stems, leaves and flowers.

It is the second stage of cell division, between prophase and anaphase. The chromosomes become attached to the spindle fibres on the equator.

Abscisic acid (ABA) plays a central role in many aspects of plant growth, including seed development, dormancy and germination. It also causes abscission of leaves.

Sucrose and starch are more efficient in energy storage as compared to glucose and fructose, but starch is insoluble in water. So, it cannot be transported via phloem. Sucrose, being water soluble and energy efficient, is chosen to be the carrier of energy from leaves to different parts of a plant.

Sporopollenin is one of the most chemically inert biological polymers. It is a major component of the tough outer (exine) walls of plant spores and pollen grains. It is chemically very stable and is usually well preserved in soil.

In bryophytes, the calyptra is an enlarged archegonial venter that protects the capsule that contains the embryonic sporophyte. The calyptra is usually lost before the spores are released from the capsule.

These are the coding sequences which code for a protein or RNA.

Aeolian or eolian refers to things related to Aeolus, the Greek God of wind. Hence, the soil that is transported by the wind is called as eolian soil.

It belongs to family Malvaceae. Its floral formula is ♀, Epi 3, K 5, C (5), A (α), G (α).

Agar or agar-agar is a jelly-like substance that is obtained from red algae Gelidium.

The small branches at each septum are termed as clamp connections. It is believed that the formation of clamp connections, where they occur in the dikaryons of some species, function in ensuring that each cell is binucleate.

Transposon is a DNA sequence that can change its position within a genome, sometimes creating or reversing mutations and altering the cell's genome size.

Edge effect refers to the change in population or community structure that occurs at the boundary of two habitats. Areas with small habitat fragments exhibit especially pronounced edge effects that may extend throughout the range.

Pollination in Cycas occurs at three celled stage (prothalial cell, generative cell and a tube cell).

The concept of limiting factors states that growth is controlled not by the total amount of resources available, but by the scarcest resource. It was given by Blackman.

According to 10% law, during the transfer of energy from organic food from one trophic level to the next, only about 10% of the energy from organic matter is stored as flesh. The remaining is lost during transfer, broken down in respiration or lost to incomplete digestion by higher trophic levels.

Double fertilisation is a complex fertilisation mechanism of flowering plants (angiosperms). This process involves the joining of a female gametophyte (megagametophyte, also called the embryo sac) with two male gametes (sperm). It occurs in angiosperms.

Vernalisation is the induction of a plant's flowering process by exposure to the prolonged cold of winter or by an artificial equivalent.

Organotroph is an organism that obtains hydrogen or electrons from organic substrates. It is usually a decomposer.

Deforestation is the permanent destruction of forests in order to make the land available for other uses. It is the main cause of extinction of some species in tropical forests.

A lithosere is a plant succession that begins life on a newly exposed rock surface. Lichen is the primary vegetation to grow there.

Apoptosis is a process of programmed cell death that occurs in multicellular organisms.

It is a chromosome with the centromere so placed that it divides the chromosome into two arms of strikingly unequal length. Thus, it forms the L-shape.