Reproduction in flowering plants

What is the difference between sexual and asexual reproduction in plants?

Sexual: Fusion of male/female gametes, creating genetic variation.
Asexual (Vegetative): One parent, creating genetically identical clones.

Why are both sexual and asexual reproduction significant in agriculture?

Asexual: Used for rapid propagation of desirable varieties.
Sexual: Used to create new/improved food crops (including via polyploidy).

What are the two parts of the stamen (male flower part) and their functions?

Anther: Produces and contains pollen grains.
Filament: Stalk that supports the anther for dispersal.

What are the four parts of the carpel/pistil (female flower part) and their functions?

Stigma: Sticky tip that receives pollen.
Style: Tube pollen travels down.
Ovary: Base containing ovules.
Ovule: Contains female gametes (egg cell).

What are the functions of petals and sepals?

Petal: Colorful to attract pollinators.
Sepal: Protects the flower bud before it opens.

Why is meiosis essential in the formation of plant gametes?

It halves the chromosomal number so the diploid number is fully restored upon fertilization.

Describe the process of microsporogenesis (male gamete formation).

A diploid cell (2n) in the anther undergoes meiosis to produce four haploid microspores, which develop into pollen grains.

What two nuclei are found in a mature pollen grain, and what does the generative nucleus do?

Contains a <b>tube nucleus</b> and a <b>generative nucleus</b>. The generative nucleus divides to form two sperm cells.

Describe the process of megasporogenesis (female gamete formation).

A diploid cell in the ovule undergoes meiosis to produce four megaspores, but only one survives to develop into the embryo sac.

What is the cellular and nuclear composition of a mature embryo sac?

It contains 7 cells and 8 nuclei, including one egg cell and two polar nuclei.

What is pollination and what are its two main types?

The physical transfer of pollen from anther to stigma.<br><b>Self-pollination:</b> Within the same plant/flower.<br><b>Cross-pollination:</b> Between different plants of the same species.

How do wind-pollinated flowers differ from insect-pollinated flowers?

Wind-pollinated: Light pollen and feathery stigmas.
Insect-pollinated: Bright petals, scents, and nectar.

How does the pollen tube reach the ovule during fertilization?

It grows down the style and enters the ovule through a tiny opening called the <b>micropyle</b>.

What happens during the first fertilization event of double fertilization?

One sperm cell fuses with the egg cell to form a diploid zygote (2n), which becomes the embryo.

What happens during the second fertilization event of double fertilization?

The second sperm cell fuses with two polar nuclei to form a triploid endosperm (3n).

What is the structural role of the endosperm?

It serves as food storage tissue for the growing plant embryo.

What post-fertilization transformations turn flower parts into seed and fruit structures?

The <b>ovule</b> becomes the seed, and the <b>ovary</b> matures into the fruit.

What is the primary reproductive purpose of a fruit?

It serves as a delivery mechanism for seed dispersal.

What are the main anatomical components of a seed?

A seed coat (testa) for protection, the endosperm for food, and the embryo.

What do the radicle and plumule of a plant embryo develop into?

Radicle: Future root.
Plumule: Future shoot.

What are the three core environmental requirements for seed germination?

1. Water (activates enzymes)<br>2. Oxygen (for respiration)<br>3. Suitable temperature

What are the physiological steps of seed germination?

Seed absorbs water -> Enzymes activate -> Radicle grows downward -> Shoot grows upward.

How are genetic engineering, cloning, and seed banks used in modern agriculture?

Engineering/Cloning: Produces high-yield or disease-resistant varieties.
Seed Banks: Maintains biodiversity by storing seeds for the future.

What are the agricultural uses of the plant hormones auxins and gibberellins?

Auxins: Promote rooting in cuttings.
Gibberellins: Increase fruit size.

What is polyploidy and what is its benefit in commercial farming?

Having extra chromosome sets; it results in larger, more robust commercial fruits (e.g., seedless watermelons).

Compare the transport directions and structural compositions of xylem and phloem.

Xylem: Transports water/minerals upward; made of dead cells with thick walls.
Phloem: Transports manufactured food (sucrose) in both directions (translocation).