Plant Biology: Classification, Nutrition, and Reproduction

General Plant Features

Plants are multicellular, autotrophic eukaryotes. They possess cell walls and chloroplasts, and they reproduce through both sexual and asexual means. Most are sessile.

Plant Classification

• Non-flowering plants: Mosses, liverworts, and ferns.
• Flowering plants: Gymnosperms (seeds not enclosed in fruit) and Angiosperms (seeds enclosed in fruit).

Mosses and Liverworts

These are small (approx. 1 cm), live in damp environments, and lack conducting vessels. They do not have true roots, stems, or leaves; instead, they have rhizoids (false roots), cauloids (false stems), and phyllodes (false leaves). They reproduce via spores. Liverworts have rounded leaves, while mosses have sharpened leaves.

Ferns

Ferns can grow to several meters in height and thrive in damp areas. They possess conducting vessels, underground stems (rhizomes), roots, and leaves (fronds). They reproduce via spores.

Gymnosperms

Mostly large trees or shrubs with perennial, needle-like leaves (e.g., cypress, pine, fir, juniper). They produce small, inconspicuous flowers arranged in cones. Each plant typically produces both male and female reproductive structures.

Angiosperms

Varied in size and found in all environments. Most are deciduous. They feature seeds protected by fruit and brightly colored, often hermaphroditic flowers to attract pollinators. Examples include wheat, tulips, roses, and sunflowers.

Plant Nutrition

Nutrition involves the root, stem, and leaf.

• Root: Absorbs water and mineral salts, anchors the plant, and stores substances (e.g., carrots, beets). Types include fasciculate and taproot (axonomorfa).
• Leaf: Primary site for photosynthesis.

Metabolic Processes

• Photosynthesis: H2O + mineral salts (raw sap) + CO2 → Organic material + O2.
• Cellular Respiration: Organic material + O2 → Energy + CO2 (occurs day and night).

Relationship and Movement

Plant movements can be transitory (e.g., sunflowers tracking the sun) or permanent (e.g., root growth).

Reproduction

• Asexual: Does not involve specialized cells.
• Sexual: Involves specialized cells.

Pollination and Fertilization

Pollination: The transport of pollen grains to the stigma, facilitated by water, wind, or animals (insects and birds).

Fertilization: The union of pollen and the egg cell to form a seed. The ovary develops into a fruit, which contains the seed. The fruit consists of a pericarp surrounding the seed, which contains an embryo, food reserves, and a protective cover.

• Dry Pericarp: Poppy, nuts, acorns, beans, almonds.
• Fleshy Pericarp: Cherry, tomato, peach, orange, pear, melon, grapes.