Reproduction

(a) (i) - Process of Double Fertilization:
1. Pollen germination: Pollen grain germinates on the stigma, forming a pollen tube that grows through the style and enters the ovule via the micropyle.
2. Synergids: One synergid guides the pollen tube into the embryo sac.
3. Fertilization I (Syngamy): One male gamete fuses with the egg cell, forming a diploid zygote (2n).
4. Fertilization II (Triple Fusion): The second male gamete fuses with two polar nuclei in the central cell to form a triploid primary endosperm nucleus (3n).
- Ploidy of end products:
-- Zygote: Diploid (2n)
-- Endosperm: Triploid (3n)
(ii) The endosperm develops before the embryo because it provides essential nutrients for the developing embryo, supporting its early growth and establishment.
OR
(b) (i) - Site of fertilization: The ampullary region of the fallopian tube.
- Process of fertilization:
1. The sperm reaches the ovum in the fallopian tube.
2. The sperm penetrates the zona pellucida layer of the ovum using acrosomal enzymes.
3. The sperm nucleus fuses with the egg nucleus, forming a diploid zygote.
- Prevention of polyspermy:
- Cortical reaction: Once the sperm enters the ovum, cortical granules are released, altering the zona pellucida structure and preventing other sperms from entering.
(ii) - Embryonic stage: The blastocyst.
- Process of implantation:
1. The blastocyst reaches the uterus and attaches to the endometrial lining.
2. The trophoblast cells of the blastocyst invade the endometrium.
3. The endometrium grows around the blastocyst, anchoring it securely.

(a) - Site of action of FSH: FSH (Follicle-Stimulating Hormone) acts on the Sertoli cells in the seminiferous tubules of the testes.
- Action of FSH: It stimulates Sertoli cells to secrete androgen-binding protein (ABP). ABP maintains a high concentration of testosterone in the seminiferous tubules, which is essential for the progression of spermatogenesis.
OR
- Role of LH in spermatogenesis: LH (Luteinizing Hormone) acts on the Leydig cells located in the interstitial space of the testes. It stimulates the Leydig cells to secrete testosterone, which plays a crucial role in the initiation and maintenance of spermatogenesis.
(b) (i) - Cells: Spermatogonia
- Product: Primary Spermatocytes
(ii) - Meiosis I:
-- Cells: Primary Spermatocytes
-- Product: Secondary Spermatocytes
- Meiosis II:
-- Cells: Secondary Spermatocytes
-- Product: Spermatids
(c) The sperms travel through the following accessory ducts:
1. Rete testis
2. Vasa efferentia
3. Epididymis

(a) IVF is so named because it involves fertilization that occurs outside the body (in vitro), meaning in a laboratory dish. The sperm and egg are combined in a petri dish for fertilization, and the resulting zygote is then implanted into the woman’s uterus.
Importance: IVF helps in overcoming infertility in cases where other treatments have failed. It is particularly useful for women with blocked fallopian tubes, male infertility, or unexplained infertility.
(b) - GIFT (Gamete Intra-Fallopian Transfer): In GIFT, eggs and sperm are placed directly into the fallopian tubes, where fertilization occurs naturally inside the body.
- ZIFT (Zygote Intra-Fallopian Transfer): In ZIFT, fertilization occurs outside the body (in vitro), and the resulting zygote is transferred into the fallopian tube.

(a) Two copper-releasing intra-uterine devices (IUDs) are: 1. Copper-T 2. Multiload Cu375
These IUDs are effective contraceptives because: 1. They release copper ions, which create a hostile environment in the uterus, preventing sperm from fertilizing the egg. 2. They cause changes in the cervical mucus, making it thicker and less penetrable by sperm.
(b) Two outbreeding devices developed by flowering plants to encourage cross-pollination are: 1. Brightly colored flowers: The bright colors attract pollinators like bees, birds, and butterflies, encouraging the transfer of pollen from one flower to another. 2. Different flowering times: Plants may have different flowering periods to ensure that they do not self-pollinate, thus promoting cross-pollination when different species or individuals flower at different times.