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Repro in Plants Unit 3.1a TYS MCQ 1. C 2. A 3. D 4. B 5. B 6. D 7. A 8. C 9. C
10. D 11. A 12. B
• The vegetaFve nucleus controls the growth of the pollen tube. [1/2] • Enzymes are secreted to digest the Fssues of the sFgma & style. [1/2] • The pollen tube penetrates right through the style as it grows, and enters the embryo sac of the ovule, usually through the micropyle; • Along the way, the generaFve nucleus divides to form 2 male gametes. [1/2] • The vegetaFve nucleus disintegrates before reaching the embryo sac. [1/2] • Within the embryo sac, the Fp of the pollen tube absorbs sap and bursts, releasing the two male gametes;
Essay QuesFon 2b AdaptaFon • Asexual ReproducFon • Sexual reproducFon – Self & Cross pollinaFon
Essay QuesFon 2aii
Describe the process of FerFlisaFon in a Flowering Plant
• FerFlisaFon happens aNer pollinaFon – the pollen grains have reached the sFgma from the anther; • The pollen grain grows into a pollen tube. This is sFmulated by the sugary fluid secreted by the mature sFgma; • The cytoplasm of a pollen tube has two nuclei: vegetaFve & generaFve nuclei;
• One gamete fuses with the ovum to form a zygote; • The other gamete fuses with the definiFve nucleus to form an endosperm nucleus.
Asexual ReproducFon • 1 parent cell • Cell division by mitosis • GeneFcally idenFcal offsprings • No variety • Hence, No new characterisFcs that help to adapt to new surroundings.
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Sexual ReproducFon‐ Self PollinaFon • 2 parent cells but from same plant • Cell division to produce gametes by meiosis • Pollen grains and Ovules have different combinaFons of parental genes. • GeneFcally different offsprings (similar) • more variety than asexual reproducFon. • Able to adapt to new surroundings beger.
Sexual ReproducFon‐ Cross PollinaFon • 2 parent cells from different plants • Unique characterisFcs inherited • Cell division to produce gametes by meiosis • Pollen grains and Ovules have different combinaFons of parental genes. • GeneFcally different offsprings • Gene pool is wider hence more variety of offsprings than in self pollinaFon. • Unique characterisFcs ‐ Able to adapt to new surroundings beger and increase survival.
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