UPCAT Biology — Plants (Botany)Flash Cards

What are plants and what makes them unique from other organisms?

Plants are multicellular, autotrophic organisms that produce their own food through photosynthesis. They contain chlorophyll (green pigment) that captures light energy and converts it into chemical energy. Unlike animals, plants make their own food using sunlight, carbon dioxide, and water.

Define autotroph and give examples.

An autotroph is a 'self-feeder' organism that produces organic compounds from inorganic substances like water and CO2. Examples include plants, algae, and some bacteria. They form the foundation of food chains by converting light energy into chemical energy that other organisms can use.

What is the difference between heterotroph and autotroph?

Autotrophs produce their own food from inorganic substances (plants, algae). Heterotrophs obtain carbon by consuming existing organic molecules made by other organisms (animals, fungi, many microbes). Autotrophs are producers; heterotrophs are consumers.

List the main parts of algae and their functions.

1. Thallus (Frond) - main body of algae; 2. Blade - large, flattened, leaf-like structure; 3. Stipe - stem-like structure without vascular tissues; 4. Holdfast - root-like structure for anchorage; 5. Gas Bladder - air bladder that maintains upright position in water.

Compare the three types of algae: Red, Brown, and Green.

Red Algae (Rhodophyta): mainly marine, red color, chlorophyll a+d, floridean starch storage. Brown Algae (Phaeophyta): exclusively marine, olive-brown, chlorophyll a+c, laminarin storage. Green Algae (Chlorophyta): mainly freshwater, chlorophyll a+b, starch storage, mostly unicellular and motile.

What are bryophytes and why are they called 'amphibians of plant kingdom'?

Bryophytes are non-vascular plants (mosses, liverworts, hornworts) found in both land and water environments. They're called 'amphibians of plant kingdom' because they can survive in both terrestrial and aquatic habitats, bridging the gap between fully aquatic and terrestrial plants.

What is the difference between antheridium and archegonium?

Antheridium: male reproductive organ, rounded outline, produces many motile sperm (antherozoids), no sterile cells inside. Archegonium: female reproductive organ, flask-shaped, contains sterile cells inside, produces single non-motile egg cell.

Describe the bryophyte life cycle and why they need water for reproduction.

Bryophytes show alternation of generations: haploid gametophyte (independent) produces gametes → fertilization forms diploid sporophyte (dependent on gametophyte) → sporophyte produces spores through meiosis → spores germinate into gametophyte. Water is needed for sperm to swim from antheridium to archegonium for fertilization.

What are the four divisions of pteridophytes (spore-producing vascular plants)?

1. Psilophyta (psilotums) - most primitive, often leafless; 2. Lycophyta (club mosses) - microphyllous leaves; 3. Sphenophyta (horsetails) - only Equisetum exists, scaly leaves in whorls; 4. Pterophyta (ferns) - macrophyllous leaves called fronds.

What is the difference between gymnosperms and angiosperms?

Gymnosperms: non-flowering, naked seeds (no ovary), wind pollination, perennial and xerophytic, examples: pines, cycads. Angiosperms: flowering plants, seeds enclosed in ovary, various pollination methods, double fertilization occurs, most commercial plants, examples: monocots and dicots.

List the key differences between monocots and dicots.

Monocots: 1 cotyledon, parallel leaf veins, scattered vascular bundles, flower parts in 3s, fibrous roots. Dicots: 2 cotyledons, netted leaf veins, vascular bundles in rings, flower parts in 4s/5s, taproot system.

Compare the three types of ground tissue in plants.

Parenchyma: living cells, thin cellulose walls, food storage, has nucleus and large vacuole. Collenchyma: living cells, thick cellulose/pectin walls, mechanical support, distinct nucleus. Sclerenchyma: dead cells, lignin walls, mechanical rigidity, no nucleus/cytoplasm.

What are the functions of xylem and phloem in vascular plants?

Xylem: transports water and dissolved minerals from roots to leaves, provides structural support, composed of dead cells. Phloem: transports organic nutrients (sugars) from leaves to all plant parts, composed of living cells, includes sieve tubes and companion cells.

Write the chemical equation for photosynthesis and explain what it represents.

6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂. This represents plants using 6 molecules of carbon dioxide and 6 molecules of water, with light energy, to produce 1 molecule of glucose and 6 molecules of oxygen. It converts light energy into chemical energy stored in glucose bonds.

What are the two main stages of photosynthesis and where do they occur?

Light Reactions: occur in thylakoid membranes, require continuous light, produce ATP and NADPH, convert water to oxygen. Carbon Reactions (Calvin Cycle): occur in stroma, don't directly need light, use ATP and NADPH to fix CO₂ into glucose (G3P molecules).

What is chlorophyll and what are accessory pigments?

Chlorophyll a: most abundant green photosynthetic pigment that captures light energy. Accessory pigments: energy-capturing molecules other than chlorophyll a that absorb wavelengths chlorophyll a cannot absorb. Examples include chlorophyll b and carotenoids in plants.

Describe the structure of a chloroplast and its photosynthetic components.

Chloroplast contains: Stroma (gelatinous fluid where carbon reactions occur), Grana (stacks of thylakoid membranes where light reactions occur), Thylakoid membranes (contain photosynthetic pigments and photosystems), Thylakoid space (enclosed by thylakoid membranes).

What are stomata and what is their function in plants?

Stomata are tiny pores on plant leaves that allow gas exchange between the plant and environment. They permit CO₂ to enter for photosynthesis and O₂ to exit. They also allow water vapor to escape during transpiration, helping regulate plant temperature and water loss.

Define transpiration and explain its importance in plants.

Transpiration is the process where plants release water as moisture or water vapor through stems, leaves, and flowers. It helps: cool the plant, transport minerals from roots to leaves, maintain plant structure through turgor pressure, and drive the water transport system.

What are the main parts of a flower and their functions?

Petals: colorful parts that attract pollinators. Sepals: green leafy parts that protect flower buds. Stamens: male parts consisting of anther (produces pollen) and filament (supports anther). Pistil: female part consisting of stigma (receives pollen), style (connects stigma to ovary), and ovary (contains eggs).