Given below are two statements: One labelled as Assertion A and the other labelled as Reason R: Assertion A: In gymnosperms the pollen grains are released from the microsporangium and carried by air currents. Reason R: Air currents carry the pollen grains to the mouth of the archegonia where the male gametes are discharged and pollen tube is not formed. In the light of the above statements, choose the correct answer from the options given below:
Both A and R are true but R is NOT the current explanation of A
A is true but R is false
A is false but R is true
Both A and R are true and R is the correct explanation of A
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The Correct Option isB
Approach Solution - 1
To determine the correctness of the provided statements about gymnosperms, we start by analyzing both the assertion and reason given in the context of biological knowledge about gymnosperms.
Assertion (A): In gymnosperms, the pollen grains are released from the microsporangium and carried by air currents.
This assertion is true. In gymnosperms, the process of pollination is typically anemophilous, meaning wind-pollinated. Pollen grains are indeed released from the microsporangium and dispersed by air currents to reach the female cones.
Reason (R): Air currents carry the pollen grains to the mouth of the archegonia where the male gametes are discharged and pollen tube is not formed.
This reason is false. In gymnosperms, after pollination, a pollen tube is formed. The pollen tube grows towards the female gametophyte to facilitate the transfer of male gametes, and this defines the mode of fertilization in gymnosperms. Therefore, the statement that pollen tube is not formed is incorrect.
Option
Description
Both A and R are true but R is NOT the current explanation of A
Only A is true; R is false.
A is true but R is false
This option accurately reflects the true and false statements.
A is false but R is true
A is true, while R is false.
Both A and R are true and R is the correct explanation of A
R is not true, hence cannot be the explanation.
Therefore, the correct option is: A is true but R is false.
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Approach Solution -2
Assertion A is true. Gymnosperms do release their pollen grains from the microsporangia, and these pollen grains are often carried by air currents for pollination. However, Reason R is incorrect. Air currents do play a role in carrying pollen grains, but the pollen grains are not carried to the mouth of the archegonia. In gymnosperms, the male gametes are indeed discharged from the pollen tube, which grows from the pollen grain towards the archegonia. The pollen tube delivers the male gametes to the vicinity of the ovule, allowing fertilization to occur.
Therefore, The correct option is (B): A is true but R is false
Gymnosperms are flowerless plants that produce cones and seeds. It literally means "naked seed". They sit exposed on the surface of leaf-like structures called bracts. Gymnosperms are vascular plants of the subkingdom Embyophyta and include conifers, cycads, ginkgoes, and gnetophytes. They are abundant in temperate forest and boreal forest biomes with species that can tolerate moist or dry conditions.
Characteristics of Gymnosperms
They do not produce flowers.
Seeds are not formed inside a fruit.
They are found in colder regions where snowfall occurs.
They form cones with reproductive structures.
Xylem does not have vessels and the phloem and it has no companion cells and sieve tubes.