Question

4. What four cells make up the pollen grain in Conifers?

5. Are coniferous sperm flagellated?

6. Where does fertilization occur and what structure becomes a seed in pine trees?

7. Explain double fertilization

8. Name the structures that precede the ones listed in the life cycle of a seed plant.

1. ____________ Female gametophyte

2. ____________ Male gametophyte

c. _____________ Adult sporophyte

9. What are the three parts of a seed in angiosperm

10. Compare conifers to flowering plants by completing the following table:

	Dominant Generation	Vascular Tissue (Present or Absent)	Dispersal of Offspring	Fruit (Present or Absent)
Conifer
Flowering plant

11. Compare the location of the ovule in the pine and the flowering plant.

12. What is the difference between pollination and fertilization?

Answer 1

Ans1) Four cells that make up the pollen of conifers are two prothallial cells , one generative cell and one tube cell. After pollination the prothallial cell degenerates while the tube cell develops into pollen tube and the generative cell divides mitotically to produce a sterile cell and a spermatogenous cell which divide prior to fertilisation to produce two male gametes.

Ans2) Conifers sperms are non flagellated because they have pollen tube through which sperm move to the ovule and mated with female gamete.

Ans3)Fertilization in pine trees occurs in ovule where male gamete fuses with female gamete to produce a diploid zygote. Embryo is formed by development of zygote. After embryo formation ovule is changed into seed.

Ans4)Double fertilisation is the unique feature of angiosperms where one haploid male gamete fuses with the haploid egg to form diploid zygote that is called syngamy while second haploid male gamete fuses with the secondary nucleus of central cell(2n) to produce a triploid endosperm nucleus that is called as Triple fusion. Since two different cells of embryo sac are fertilized hence , the fertilisation is called as double fertilisation (syngamy& triple fusion) .

Ans5) a) Megaspore female gametophte

B) microspore  Male  gametophyte

C) seed. Adult Sporophyte.

Ans6)

	Dominant Generation	Vascular Tissue (Present or Absent)	Dispersal of Offspring	Fruit (Present or Absent)
Conifer	Sporophyte	Present	Through seed dispersal	Absent
Flowering plant	Sporophyte	Present	Through dispersal of seeds enclosed in Fruits	Present

Ans7)In pine tree ovule is present on the upper surface of seed cone scales while in flowering plant ovule is present inside the ovary.

Ans8) Pollination is the process of transfer of pollen grains from male cone to seed cone in case of gymnosperms, while  from anther to stigma in case of flowering plants. Fertilization is the process of fusion of haploid male gamete and haploid female gamete to produce diploid zygote.