Download App

Sexual Reproduction in Flowering Plants — BIOLOGY STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceBIOLOGYSexual Reproduction in Flowering Plants3 Marks
Question
What does an interaction between pollen grain and its compatible stigma result in, after pollination? List two steps in sequence that follow after the process.
✓

Answer

Events in pollen-pistil interaction:
  1. A compatible pollen grain starts its germination on the stigma.
  2. The intine grows out through one of the germ pores to form a pollen tube; the contents of the pollen grain move into the pollen tube.
  3. In those species, where the pollen grains are shed at the two-celled stage, the generative cell divides to form two male gametes.
  4. The pollen tube grows through the tissues of style and stigma and reaches the ovary.
  5. It enters the ovule through the micropyle and then enters the embryo sac through the filiform apparatus of one of the synergids.
  6. All these events, from the deposition of pollen grains on the stigma till the entry of pollen tube into the ovule, are collectively called pollen-pistil interaction.
The two events that follow this are:
  1. Syngamy, i.e., fusion of male and female gametes to form a zygote.
  2. Triple fusion, i.e., fusion of two polar nuclei (secondary nucleus) and a male gamete, to form the primary endosperm nucleus (PEN).

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "3 Marks Question" from Sexual Reproduction in Flowering Plants→Sexual Reproduction in Flowering Plants — all question types→BIOLOGY STD 12 Science question papers→Rajasthan Board STD 12 Science question papers→Rajasthan Board question paper generator→

Similar questions

A. Diagram given below depicts different species of Warbler birds feeding on different regions on a Spruce tree. Explain the mechanism which helps them to co-exist.
Image
B. What does Gause's exclusion principle state? Does it apply in the case shown above? Explain.
→
Answer the following questions:
What are biopesticides? Give any two examples of their application.
→
Study a part of the life cycle of malarial parasite given below. Answer the questions that follow:

  1. Mention the roles of 'A' in the life cycle of the malarial parasite.
  2. Name the event 'C' and the organ where this event occurs.
  3. Identify the organ 'B' and name the cells being released from it.
→
Seeing a crowd of students in one corner of the school, the principal rushed to see the matter and found some children beating and chasing a small lizard. On seeing the principal, all the children fled to their classes except Alok who requested the principal to arrange for some medical assistance for the injured animal. The principal rewarded Alok for his attitude to save guard our biodiversity.
  1. Mention the factors resulting in loss of biodiversity
  2. Was Alok an indisciplined boy, who did not run to the class on seeing the principal? What values does the act promote?
→
A person is suffering from Ascariasis. Mention the pathogen causing the disease and an organ of the body affected, three symptoms and one mode of transmission of the disease.
→
Define the following-
(A) Food Web
(B) decomposer
(C) Standing Crop
→
Would you consider the wings of butterfly and a bat as a homologous or analogous?
→
Suggest and explain any three Assisted Reproductive Technologies (ART) to an infertile couple.
→
Autotrophs convert inorganic materials into organic material with the help of solar energy.

  1. Name the process depicted by the given statement.
  2. Name the pigment which traps solar energy and convert light energy to chemical energy.
  3. What do you understand by a photosynthetic unit?

$6\text{CO}_2+12\text{H}_2\text{O}\xrightarrow{\text{Light}}\text{C}_6\text{H}_{12}\text{O}+6\text{H}_2\text{O}+6\text{O}_2$

→
What is artificial selection? Do you think it affects the process of natural selection? How?
→