Plants have developed many mechanisms to encourage cross-pollination that include:
I. | Asynchrony between pollen release and stigma receptivity |
II. | Placing of pollen and stigma at different positions |
III. | Self-incompatibility |
IV. | Dioecy |
What would be true regarding these mechanisms?
1. | I and II prevent autogamy and geitonogamy |
2. | III is a genetic mechanism that inhibits pollen germination or pollen tube growth |
3. | IV is a very common [found in the majority] mechanism seen in flowering plants |
4. | I, II, and III invariably lead to xenogamy |
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The correct description of the structure shown in the figure would be:
1. | Anatropous ovule; 1 – Nucellus; 2 – Chalaza; 3 – Raphe; 4 – Funiculus |
2. | Orthotropous ovule; 1 – Nucellus; 2 – Micropyle; 3 – Raphe; 4 – Funiculus |
3. | Anatropous ovule; 1 – Nucellus; 2 – Chalaza; 3 – Funiculus; 4 – Raphe |
4. | Anatropous ovule; 1 – Nucellus; 2 – Micropyle; 3 – Raphe; 4 – Funiculus |
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Three air-dried bean seeds are tied to a glass slide with two [A and C in the fig.] at the two ends and one [B] in the middle. This slide is placed in a beaker with the middle seed half immersed in water as shown in the fig. The water level is kept constant throughout the experiment. Which seed/s is/are expected to germinate normally?
1. | Only A | 2. | Only B |
3. | Only B and C | 4. | Only A and C |
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Identify the incorrectly matched pair:
1. |
Triploid nutritive tissue of a seed deposited externally to the embryo sac |
Perisperm |
2. |
The tissue that arises from the ripened ovary wall of a fruit; the fruit wall |
Pericarp |
3. |
The natural or artificially induced production of fruit without fertilisation of ovules |
Parthenocarpy |
4. |
Asexual reproduction where the growth and development of embryos occur without fertilization by sperm |
Parthenogenesis |
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Double fertilization is:
1. | Seen in some flowering plants |
2. | In seen in many flowering plants |
3. | Is seen in both flowering and non-flowering plants |
4. | Is a unique event of flowering plants |
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Pollens grains are long ribbon-like and are carried passively in water in:
1. | female plants remain submerged in water |
2. | male plants remain submerged in water |
3. | both male and female plants remain submerged in water |
4. | both male and female plants reach the surface of the water. |
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Majority of plants:
1. | Use abiotic agents for pollination |
2. | Use biotic agents for pollination |
3. | Do not use any agent for pollination |
4. | Use both abiotic and biotic agents for pollination. |
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Transfer of pollens from the anther to the stigma of the same flower is called:
1. | Autogamy | 2. | Geitonogamy |
3. | Xenogamy | 4. | Cleistogamy |
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In over 60 % of angiosperms, pollen grains are shed at:
1. | 2-celled stage | 2. | 3-celled stage |
3. | 4-celled stage | 4. | 1-celled stage |
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The outer hard layer of the pollen wall is made up of:
1. | Callose, which is easily digested by enzymes |
2. | Sporopollenin, which is resistant to all enzymes |
3. | Hemicellulose, which is difficult to digest by enzymes |
4. | Calcium pectate, which is easily digested by enzymes |
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