Test: Sexual Reproduction in Flowering Plants - 2 - NEET MCQ

• It’s the nucellus. Nucellus is the place where the embryo sac rests.
• It is made up of cushiony cells called parenchymatous cells.
• Nucellus helps in the nourishment of the embryo sac.

• They are the 3 mature cells in the embryo sac present opposite to the micropylar end.
• The function of the antipodal cells is to provide nutrition and nourishment to the embryo sac.

The microsporangial wall’s outer three layers—the epidermis, endothecium, and middle layers—help to shield developing anthers and act as a mechanism for dehiscence in adult anthers.

• Zygotes split following endosperm development.
• The zygote cannot sustain itself by nourishment, hence the explanation.
• It needs endosperm to get its nourishment. It is a modification.

The mature anther consists of four microsporangia which contain four layers. The inner most layer is called tapetum that provide nutrient to growing microspores and tissues inside it are called microspore mother cell that produce pollen grain.

To form 64 pollen grains, 16 meiotic divisions are needed. Here's the detailed breakdown:

- Each meiotic division results in the formation of 4 pollen grains.
- So, to calculate the total number of meiotic divisions required: 64 pollen grains ÷ 4 pollen grains per division = 16 meiotic divisions.

Therefore, the correct answer is C: 16.

Filiform apparatus is finger-like projection attached with egg apparatus. This apparatus guide the pollen tube carrying male gametes for facilitating Syngamy.

Each Sporogenous cell under meiotic division to form tetrad of megaspores. The three megaspores degenerate and only one megaspore develops into embryo sac or female gametophyte.

Microsporangium is surrounded by four wall layers. The innermost layer is tapetum. Tapetum nourishes the developing pollens. The three outer walls provide protection and help in dehiscence of anther to release pollen grains.

Each microsporangium has 100 microspore mother cells which by meiosis form 400 microspores ( 100 × 4). In an anther there are four microsporangia , so, total number of microspores will be 4 × 400 = 1600 4 × 400 = 1600 . As each microspore forms one male gametophyte, hence , 1600 male gametophytes can be produced.

Pollen grain consists of hard covering of exine but their viability may lost with time. For Hybridisation pollen grains are collected and stored in liquid nitrogen below -196 degree Celsius temperature.

Inbreeding depression is the reduced biological fitness in a given population as a result of inbreeding, or breeding of related individuals. Continued self-pollination reduces the fertility and even productivity of the plant.
Thus, the correct answer is option A.

Large amount of fossilized pollen grain are found during excavation process of older parts due to tough covering of Sporopollenin that make the outer wall of pollen grain, exine. This substance cannot be hydrolyzed by any enzyme known.

• Embryogeny is the study of the changes that take place when an embryo develops from a zygote.
• It occurs near the embryo sac’s micropylar end.
• The nucellus and integuments unite at the base of the ovule, or chalaza, in plants.
• It can be found on an ovule opposite the micropylar end.
• Chalaza is the pathway via which plant nutrients are delivered to the nucellus.
• Three antipodal cells form from the chalazal end of the embryo sac’s cells.

• Stigma - It is the head of the pistil.
  • It receives pollen, which begins the process of fertilization.
• Style - It the stalk of the pistil.
  • It is a long, slender stalk that connects the stigma and the ovary. 
  • When pollen reaches the stigma, it begins to grow a tube through the style called a pollen tube, which eventually reaches the ovary.
• Ovary - It is the base of the pistil.
  • It holds the ovules for fertilization.
• Thalamus - It is present near the stalk of the flower.
  • It supplies nutrients to the flower.
  • It is a condensed axis of the flower from which all floral parts arise.

Endosperm cells are triploid as they are formed by triple fission of two polar nuclei and one male gamete. So, haploid cell will contain 8 chromosomes only. Root cells are diploid. Hence root cell will contain 16 chromosomes.

The meiocytecell are diploid so, haploid cell will contain 16 chromosomes. The endosperm cell are formed by fusion of two polar nuclei and one male gametes so, endosperm cells are triploid that will contain 16x3= 48 chromosomes.

The female gametophyte (embryo sac) develops from a single functional megaspore. This megaspore undergoes three successive mitotic divisions to form eight nucleate embryo sacs.

The first mitotic division in the megaspore forms two nuclei. One nucleus moves towards the micropylar end while the other nucleus moves towards the chalazal end. Then, these nuclei divide at their respective ends and re-divide to form eight nucleate stages. As a result, there are four nuclei each at both the ends i.e., at the micropylar and the chalazal end in the embryo sac. At the micropylar end, out of the four nuclei only three differentiate into two synergids and one egg cell. Together they are known as the egg apparatus. Similarly, at the chalazal end, three out of four nuclei differentiates as antipodal cells. The remaining two cells (of the micropylar and the chalazal end) move towards the centre and are known as the polar nuclei, which are situated in a large central cell. Hence, at maturity, the female gametophyte appears as a 7-celled structure, though it has 8 nucleate.

Solution:

• Funicle corresponds to V. Stalk of ovule.
• Hilum corresponds to IV. Region where body of ovule fuses with funicle.
• Integument corresponds to III. One or 2 protective layers of ovule.
• Chalaza corresponds to II. Basal part of ovule.
• Nucellus corresponds to I. Mass of cells within ovule with more food.

The number of ovule present in ovary determine the number of seeds produced inside the fruit. Mango and neem produce single seed in each fruit. Lemon contain a number of seeds but orchid contain many small size seeds.

Dormancy is the state of state of inactivity during which metabolic process slows down. Seed may remain viable to several months to years depending upon type of seeds and condition.

1. Sporogenous tissue - Formation of microspore tetrad by meiosis
2. Microspore tetrad - Microspores arranged in clusters of four cells
3. Microsporogenesis - Process of formation of microspore PMC by meiosis
4. Tapetum - Nourishes pollen grains

• Statement 1:
  Parthenocarpy (the development of fruit without fertilization) can indeed be induced by the application of growth hormones like auxins or gibberellins.
  This statement is true.

• Statement 2:
  The small opening at the tip of the ovule is called the micropyle, not the germ pore. This terminology is incorrect.
  This statement is false.

• Statement 3:
  In flowering plants, the development of the endosperm (nourishing tissue) typically begins before the development of the embryo after fertilization.
  This statement is true.

• Statement 4:
  Apomixis (asexual reproduction without fertilization) has advantages in horticulture and agriculture because it allows for the production of genetically identical plants.
  This statement is true.

Statement 1: Michelia (now often classified under Magnolia) does indeed have a polycarpellary, apocarpous gynoecium, meaning it has multiple separate carpels.
Statement 2: Papaya and orchids do have many ovules present in their ovaries. This statement is correct.
Statement 3: Hibiscus does have yellowish, powdery pollen grains. This statement is correct.
Statement 4: If pistils are fused together, they form a syncarpous gynoecium, which is a single compound structure. A monocarpellary gynoecium refers to a single carpel, not a fused structure. Therefore, the statement about pistils forming a monocarpellary syncarpous gynoecium is incorrect because these terms are mutually exclusive.
Thus, Statement 4 is incorrect.