Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Sexual reproduction in plants involves the fusion of two haploid () gamete nuclei to form a diploid () zygote, resulting in offspring that are genetically different from the parents.
Flowers are the reproductive organs. The male part (stamen) consists of the anther and filament. The female part (carpel/pistil) consists of the stigma, style, ovary, and ovules.
Pollination is the transfer of pollen grains from the anther to the stigma. Cross-pollination involves different plants of the same species, while self-pollination occurs on the same plant.
Insect-pollinated flowers typically have large, brightly colored petals and sticky pollen grains to adhere to insects, whereas wind-pollinated flowers have small, dull petals and long filaments with feathery stigmas to capture airborne pollen.
Following pollination, a pollen tube grows down the style to the ovary. The male nucleus travels through the tube to reach the ovule, entering through the micropyle to fuse with the female nucleus.
After fertilization, the ovule develops into a seed, and the ovary develops into a fruit. The zygote becomes the embryo, consisting of the radicle (young root) and plumule (young shoot).
Germination requires specific environmental conditions: water (to activate enzymes), oxygen (for aerobic respiration, ), and a suitable temperature (for optimal enzyme kinetic energy).
📐Formulae
💡Examples
Problem 1:
Explain why a seed requires for germination even though it is not yet performing photosynthesis.
Solution:
The seed requires for aerobic respiration: .
Explanation:
Before the first leaves emerge and turn green, the plant cannot synthesize its own food via photosynthesis. It must break down stored starch in the cotyledons into glucose to produce energy () for growth and cell division.
Problem 2:
Identify the structural differences between wind-pollinated and insect-pollinated pollen grains.
Solution:
Wind-pollinated pollen is small, light, and produced in large quantities; insect-pollinated pollen is larger, heavier, and often has 'spikes' or sticky coatings.
Explanation:
Light pollen allows for travel over long distances via air currents, while sticky or textured surfaces ensure the pollen adheres to the bodies of visiting insects like bees.