Angiosperm Reproduction Quiz

Study Notes

Flowers are reproductive shoots of angiosperm sporophytes, attached to the stem's receptacle.
Composed of four floral organs: sepals, petals, stamens, and carpels.
Sepals and petals are sterile, while stamens produce pollen.
Stamens consist of a filament and anther, the latter containing pollen sacs.
Carpels have a long style with a stigma for pollen landing and an ovary that contains ovules.
A pistil is formed by a single carpel or fused carpels.
Complete flowers have all four floral organs; incomplete flowers lack one or more.
Clusters of flowers are referred to as inflorescences.

Pollen develops from microspores in the microsporangia of anthers.
A microspore undergoes mitosis to form a generative cell and a tube cell.
A pollen grain consists of a two-celled male gametophyte and a spore wall.
Successful pollination results in a pollen tube that delivers sperm cells to the embryo sac.

The embryo sac, or female gametophyte, develops in the ovule.
Two integuments encase the megasporangium, where one cell undergoes meiosis to produce four megaspores, with one surviving.
The surviving megaspore divides to form a large cell with eight nuclei.

Pollination in angiosperms transfers pollen from anther to stigma, facilitated by wind, water, or animals.
Wind-pollinated species, such as grasses, release large quantities of pollen.

Coevolution involves reciprocal evolutionary changes between interacting species.
Many flowering plants have adapted to specific pollinators, exhibiting coordinated flower shapes and sizes.
Example: Darwin’s prediction of a moth with a 28 cm tongue based on flower morphology.

Involves two sperm from the pollen tube entering the embryo sac.
One sperm fertilizes the egg; the other unites with polar nuclei to form triploid endosperm for nourishment.

Endosperm development typically occurs before embryo development, providing nutrient storage (in monocots) or exporting reserves to cotyledons (in eudicots).
The zygote divides to form a multicellular suspensor anchoring the embryo and a terminal cell that grows into the embryo.
Mature seeds have a hard seed coat and enter dormancy, usually containing 5–15% water.
Eudicot embryos feature a hypocotyl, radicle, and epicotyl, while monocots have one cotyledon and a scutellum.
Germination requires imbibition to absorb water; the radicle emerges first, followed by the shoot tip.

Fruits develop from ovaries, serving to protect seeds and assist in their dispersal by wind or animals.
Fruits categorized as dry (ovary dries at maturity) or fleshy (thick, soft, and sweet at maturity).
Types of fruits: simple (single/fused carpels), aggregate (multiple separate carpels in one flower), and multiple (group of flowers or inflorescence).
Accessory fruits include other floral parts.

Fragmentation allows parent plants to separate into parts that can develop into new plants.
Adventitious shoots can arise from a parent plant’s root system.
Apomixis refers to asexual seed production from diploid cells.

Human intervention in plant reproduction and genetics dates back thousands of years.
Hybridization breeds new varieties. For instance, maize is a staple crop enhanced via artificial selection.
Plant biotechnology encompasses innovations for producing useful products, including modern genetic manipulation.
Transgenic crops developed to withstand pests, tolerate herbicides, and improve nutritional content, such as “Golden Rice” for vitamin A enhancement.

Genetic engineering may transfer allergens from other species to food plants.
Some GMOs offer health benefits, such as Bt maize, which shows reduced health risks due to lower cancer-causing toxins and less fungal infection.