Test: Botany Mock Test - 4 - NEET MCQ

There are three systems of classification -artificial, natural and phylogenetic. In the natural system of classification the organisms are arranged on the basis of all known taxonomic characters instead of one or first few. These include morphological, anatomical, cytological, physiological and biochemical characters of the organisms. The artificial system is based on one or a few characters that are easily observable.
The phylogenetic system tries to organize organisms on the basis of their genetic and phylogenetic relationships besides taxonomic characters.

Abscissic acid (ABA), also known as abscisin II and dormin. It is usually found in vascular plants, some fungi and some green algae. It acts as an inhibitor because it opposes the growth of promoting effect of auxins, GA and cytokinins, thus keep their activity under control. Leaf abscission, fruit fall and dormancy occurs due to abscissic acid.

The number and types of organisms present on earth is known as biodiversity.

Flowers are highly modified shoot bearing nodes and modified floral leaves, which are meant essentially for sexual reproduction in plants.

Cellular respiration is the mechanism of breakdown of food materials within the cell to release energy and the trapping of this energy for synthesis of ATP. In cellular respiration, NADH is oxidised to NAD⁺.

ATP synthesis is linked to the development of a proton gradient across the membranes of thylakoid.

Xylem is composed of four different kinds of elements, namely, tracheids, vessels, xylem fibres and xylem parenchyma whereas companion cells are present in phloem.

The predominant stage of the moss is the presence of gametophyte which consists of two stages – the first stage is protonema and the second stage is leafy stage. Protonema stage develops directly from the spores and leafy stage develops from the secondary protonema as a lateral bud.

In guard cells, the plant hormone abscisic acid (ABA) inhibits stomatal opening and induces stomatal closure through the coordinated regulation of ion transport.

Three different genera Solanum, Petunia and Datura are placed in the family Solanaceae.

Endosperm is the nutritive tissue which provides nourishment to the embryo in seed plant. Albuminous seeds retain a part of endosperm as it is not completely used up during embryo development (e.g., wheat, maize, barley, castor, sunflower).

Photorespiration is the process by which in the presence of light plant consumes oxygen and releases carbon dioxide (instead of fixing carbon dioxide) during photosynthesis, resulting in a decrease in photosynthetic output since no ATP is produced and carbon (as well as nitrogen in the form of ammonia) is lost inevitably. In this pathway there is no synthesis of sugar, ATP or NADPH, due to which photorespiration refers to as a wasteful process. This process reduces efficiency of photosynthesis in C₃ plants.

A different enzyme is involved in each step of glycolysis because enzymes are specific for their substrates and each step involves a different chemical reaction.

Guard cells are specialized cells in the epidermis of leaves, stems and other organs that are used to control gas exchange. The guard cells are produced in pairs with a gap between them that forms a stomatal pore. Guard cells are dumbbell shaped in monocots (e.g grasses) and bean shaped in dicots.

Mosses belong to the division Bryophyta under the Plant Kingdom and do not have true roots or stems.
They have root-like structures called rhizoids for anchorage which are multicellular and branched.
Their life cycle starts from germination of a haploid spore to form a protonema, which is filamentous or thallus-like. The gametophore plant body grows from the protonema which bears the sex-organs, archegonia and antheridia on the apices.
After fertilization, the sporophyte body undergoes meiosis to give rise to haploid spores which form the gametophytic plant body. Thus, gametophyte is the predominant stage in mosses.

ABA counteracts many effects of GA such as induction of hydrolases and a-amylase in barley seedlings.

Plant families like Convolvulaceae, Solanaceae are included in the order Polymoniales mainly based on the floral characters.

Cleistogamy is a self-fertilization that occurs within a permanently closed flower. In cleistogamous flower, the anther and stigma lies close to each other. When anther dehisces in the flower buds, pollen grains come in contact with the stigma to effect pollination. Thus, cleistogamous flowers are invariably autogamous as there is no chance of cross - pollen landing on the stigma. Cleistogamous flowers produce assured seed set even in the absence of pollinators.

RuBisCO is an enzyme present in chloroplasts, involved in fixing atmospheric carbon dioxide during photosynthesis and in oxygenation of the resulting compound during photorespiration. It is the most abundant enzyme on the earth and catalyzes the carboxylation of CO₂ to ribulose 1, 5-bisphosphate, initiates photorespiration when the CO₂/O₂ ratio is low.

For bacteria to continue growing rapidly when they are shifted from an environment containing O₂, to an anaerobic environment, they must increase the rate of glycolysis.

Lenticels are raised pores in the stem of a woody plant that allows gas exchange between the atm o sp h e re and the in tern al tissu e s. Parenchymatous cells arc usually present in cortex. The ground tissue system is divided into three main zones- cortex, pcricyclc and pith. The conjoint vascular bundles usually have the phloem located only on the outer side of the xylem.

The earliest systems of classification used only gross superficial morphological characters such as habit, colour number and shape of leaves, etc.
They were based mainly on vegetative characters or on the androecium structure.

All the given statements are the characteristics of growth of an organism. Growth can be defined as an irreversible permanent increase in size of an organ or its parts or even of an individual cell.