Biology · Science General

Botany and Plant Science

5,038 Questions

Botany and plant science delve into the biological study of plant life, covering structural anatomy, physiological processes, and reproductive mechanisms. Key topics include inflorescence patterns, root modifications, and seed development, which are vital for biology sections in medical entrance exams. This collection of practice questions helps solidify understanding of complex plant functions.

Plant ReproductionPlant AnatomyRoot ModificationsInflorescence PatternsPlant Morphology

Botany and Plant Science Questions

Multiple choice botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

Pollen grain are able to tolerate extremes of temperature and desiccation because their exine consists of 

  1. Cutin

  2. Suberin

  3. Sporopollenin

  4. Callose
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Sporopollenin 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 soils and sediments. The exine layer is often intricately sculptured in species-specific patterns, allowing material recovered from (for example) lake sediments to provide useful information to palynologists about plant and fungal populations in the past. The chemical composition of sporopollenin is not exactly known, due to its unusual chemical stability and resistance to degradation by enzymes and strong chemical reagents. Analyses have revealed a mixture of biopolymers, containing mainly long chain fatty acids, phenylpropanoids, phenolics and traces of carotenoids. Tracer experiments have shown that phenylalanine is a major precursor, but other carbon sources also contribute. It is likely that sporopollenin derives from several precursors that are chemically cross-linked to form a rigid structure.

Thus, the correct answer is option C.

Multiple choice botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

Pollen grain of an angiosperm represents 

  1. Microsporophyll

  2. Megasporophyll

  3. Female gametophyte

  4. Male gametophyte
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Stamen is the male reproductive organ that consists of long slender filament and broad knob like anther; each anther lobes of anther contains two long and cylindrical microsporangia. Since, stamen bear microsporangia in anther lobes, they are also called as microsporophylls. Option A is incorrect. Gynoecium represents the megasporophyll as it carries megasporangia, i.e., the ovule, at basal part of pistil. Option B is incorrect. Megaspore represents the first cell of embryo sac/female gametophyte; depending upon the number of megaspores involved in development of female gametophyte, single/two/three successive mitotic division form eight nucleate-seven celled female gametophyte. Option C is incorrect. Pollen grain is the first cell of male gametophyte that divides mitotically to form small generative cell and large tube/vegetative cell. Pollen with small generative and large vegetative or with one vegetative cell and two male gametes is known as mature male gametophyte.

Thus, the correct answer is option D.

Multiple choice botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

Pollen grains are able to withstand extremes of temperature and desiccation because their exine is composed of 

  1. Cutin

  2. Suberin

  3. Sporopollenin

  4. Callose
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The pollen grain is the immature male gametophyte that precociously develops into mature male gametophyte through micro gametogenesis. Meiosis in microspore mother cell forms four haploid microspores which are initially covered with a common wall of callose ($\beta$ 1,3-glucan).  Microspore matures into pollen grain which is a uni-nucleate cell with the two-layered cell wall. The exine is the outer covering of pollen grain which is highly sculptured with sporopollenin; a chemically inert polymer of carotenoid ester which is highly resistant to degradation by any enzyme, as known so far.  It can withstand extremes of temperature and desiccation. Cutin is an insoluble heterogenous lipid-polymer of long chain substituted aliphatic acids which are main constituent of cuticles and serves as the waterproof substance to reduce water loss; it does not withstand extremes of temperatures and is not present in exine. Suberin is a waterproofing waxy substance which restricts the water movement to reduce the risk of embolism caused by wear and tear damage to leaf/petiole. It is not a constituent of exine. Thus, the correct answer is option C. 

Multiple choice botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

Exine of pollen grain is made up of

  1. Pectocellulose

  2. Ligno cellulose

  3. Sporopollenin

  4. Pollen Kit
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Pollen grain is a uninucleate cell with two layered cell wall. Exine is the outer covering of pollen grain which is highly sculptured with sporopollenin; a chemically inert polymer of carotenoid ester which is highly resistant to degradation by any enzyme, as known so far. Option C is correct. 

The inner thin cell layer of cellulose/pectin cellulose makes intine; this makes option A incorrect. 
Lignin may or may not be present in the outer wall which makes option B incorrect. Correct answer is B. 
The sticky oily covering found around surface of pollens is termed as pollen kit. It is not part of pollen wall. This make option D incorrect.
Therefore, the correct answer is option C.

Multiple choice botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

The pollen grain is 

  1. An immatures male gametophyte.

  2. A mature male gametophyte.

  3. Partially developed male gametophyte.

  4. Both (A) and (C)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Pollen grain is an immature male gametophyte as it has two cells out of which one develops into two male gametes after pollination. The generative cell of pollen undergoes mitosis to form two male gametes. So, pollen is a immature or partially developed male gametophyte. Correct answer is D.

Multiple choice botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

Which from the following one is odd?

  1. Micropyle

  2. Embryo sac

  3. Nucellus

  4. Pollen grain
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Micropyle is a small opening in the surface of an ovule.

Embryo sac is the structure within a plant ovule that contains the egg cell.
Nucellus is the central part of an ovule, containing the embryo sac.
Pollen grain is a microscopic body that contains the male reproductive cell of a plant.
As all other structures are part of ovule apart from Pollen grain, therefore it is odd one out. Hence, option D is correct.

Multiple choice botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

Pollen grain wings of Pinus are outgrowths of

  1. Intine

  2. Exine

  3. Exo-intine

  4. Sporangial wall
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In the Pinus, winged pollen grains exist. It is an outgrowth of exine on the two lateral sides to make the wings of pollen. It is the characteristic feature, only in Pinus. In Pinus, some surface tissues of the ovuliferous scale are still attached to the seed. Thus forming a membranous wing.

Thus the correct answer is Exine.

The correct option is B.

Multiple choice botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

Sporopollenin is part of

  1. Pollen grain covering

  2. Oosphere covering

  3. Ovule covering

  4. Cell wall
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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 soils and sediments.

So, the correct option is 'Pollen grain covering'.

Multiple choice botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

Number of nuclei present in the mature male gametophyte of angiosperms is?

  1. One

  2. Two

  3. Three

  4. Many
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Pollen grain or the male gametophyte is formed from pollen mother cells through microsporogenesis and microgametogenesis. Each pollen mother cell (PMC) divide by meiosis to form four haploid microspores (this process is called microsporogenesis). Each microspore then develops into pollen grain (this process is called mocrogametogenesis).
Each microspore divides mitotically to form two cells: a large Vegetative cell and a small Generative cell. The generative cell resides within the cytoplasm of the vegetative cell. Later, the generative cell divides to form two sperm cells (i.e. male gametes or the male nuclei). At this stage, pollen grains are said to be 3-celled. If the generative cell divides inside the pollen tube, to form two male gametes the pollen is said to be liberated at 2-celled stage. 
Thus, a mature pollen grain will always have 2 nuclei , whether liberated at 2-celled or 3-celled stage.
So, the correct answer is B.
Multiple choice botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

Ubisch bodies are connected with the formation of

  1. Sporopollenin

  2. Intine and pollenkitt

  3. Exine

  4. Pollenkitt and pollinia
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
When the anther is young, at the stage of sporogenous tissue, the cells of the Tapetum possess numerous spherical bodies called pro-Ubisch bodies or pro-orbicules. The number of pro-Ubisch bodies increases when there is meiosis in pollen mother cells. These pro-Ubisch bodies can easily cross the tapetal membrane facing the locule and during this transfer, these pro-Ubisch bodies get coated by sporopollenin and are called ubisch bodies or orbicules.
Ubisch bodies are involved in external thickening of the outer layer of pollen grain i.e. these help in exine formation.
So, the correct answer is C.
Multiple choice botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

Pollen grains are nongreen due to

  1. Absence of plastids

  2. Degeneration of plastids

  3. Conversion of plastids into chromoplasts

  4. Attraction of vectors
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Plastids are found in almost all cells of the plant body either in the form of colorless plastids or colored plastids or proplastids.

Chromoplasts are the plastids containing different colored pigments in which green colored plastids are called chloroplasts. All plastids other than chloroplasts are predominantly found in the certain class of plants and plant organs including floral parts. 
So, the correct option is 'Conversion if plastids into chromoplasts'.

Multiple choice botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

Identify the pair of wrong statements.
I. Intine of pollen grains is made up of sporopollenin.
II. Pollen grains are well preserved as fossils because of the presence of sporopollenin.
III. Enzymes can degrade the organic material of the pollen grain exine.
IV. Sporopollenin can withstand high temperature, strong acids and alkali.

  1. III, IV

  2. I, III

  3. I, II

  4. II, III
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Statement I is wrong because the exine, not the intine, is made of sporopollenin. Statement III is wrong because sporopollenin is highly resistant to enzymatic degradation, not easily degraded by them.

Multiple choice botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

Select the correct and incorrect statements.
(a) Tapetum nourishes developing pollen grains.
(b) Hilum represents junction between ovule and funicle.
(c) In aquatic plants, Water Hyacinth and Water Lily, pollination is by water.
(d) Primary endosperm nucleus is triploid.

  1. a, b correct, c, d incorrect

  2. a, b, d correct, c incorrect

  3. b, c, d correct, a incorrect

  4. a, d correct, b, c incorrect

  5. b, d correct, a, c, incorrect
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

(a) Tapetum provides nutrition to developing pollen. (b) Hilum is the junction between ovule and funicle. (d) Primary endosperm nucleus is triploid (3n) due to double fertilization. (c) is incorrect because Water Hyacinth and Water Lily are pollinated by insects or wind, not water.

Multiple choice botany male & female gametophytes: structure and development pollen grain androecium male gametophyte

Which one of the following statements is not true?

  1. Stored pollen in liquid nitrogen can be used in the crop breeding programme.

  2. Tapetum helps in dehiscence of anthers.

  3. Exine of pollen grains is made of sporopollenin.

  4. Pollen grains of many species cause severe allergies.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Tapetum is the innermost layer and completely surrounds the sporogenous tissue. The cells of Tapetum have dense cytoplasm and generally possess more than one nuclei. Tapetum nourishes the developing pollen grains.

The layer of the anther wall that helps in anther dehiscence is endothecium. The cells of endothecium develop fibrous thickenings at maturity which radiate from the inner tangential walls. These thickenings are made up of alpha cellulose and traces of lignin. These thickenings are hygroscopic and thus, help in anther dehiscence.
Hence, statement B is not true. So, the correct answer is B.