Shoot System

Parietal – polycarpellary syncarpous, unilocular, ovules on inner wall at margins of adjoining carpels; example: mustard

Step 1: Parietal placentation occurs when the ovary is polycarpellary, syncarpous and has one chamber (unilocular), with ovules attached to the inner wall where margins of adjoining carpels meet. Example: mustard, cucumber. Step 2: Free central placentation is also syncarpous and unilocular BUT the placenta is central (no septa), and ovules are on the central placenta – example: Dianthus. Option A incorrectly says multilocular. Step 3: Marginal placentation (not axile) involves a monocarpellary one-chambered ovary with ovules along fused margins – example: pea. Step 4: Basal placentation has o

Early wood (spring wood) with wider vessels formed in spring

Step 1: In temperate regions, cambium activity is seasonal. Step 2: In spring, the cambium is highly active and produces more xylem vessels with wider cavities — this is called early wood or spring wood. Step 3: In summer, the cambium is less active and produces vessels with narrow cavities — this is called late wood or summer wood. Step 4: One annual ring = one spring wood layer + one summer wood layer together. Step 5: Heart wood and sap wood are not directly related to seasonal vessel width — they relate to functional status of secondary xylem. Option A reverses the correct association.

Cymose inflorescence

Step 1: Inflorescence is the arrangement of flowers on the floral axis (peduncle). Step 2: In cymose inflorescence, the main axis terminates in a flower, thus limiting its growth. Step 3: Since the terminal flower opens first, it is the oldest. New lateral branches arise below, and their flowers open subsequently — this is called basipetal order (from apex downward). Step 4: In racemose inflorescence, the main axis keeps growing (unlimited), flowers arise in acropetal order (oldest at base, youngest at top). Step 5: Capitulum and umbel are types of racemose inflorescence, not cymose. The key i

Found in upper epidermis; lose water under high transpiration; cause leaf to roll, reducing water loss

Step 1: Bulliform cells (also called motor cells) are large, bubble-like epidermal cells present in the upper epidermis of certain monocot leaves (e.g., maize, bajra, jowar). Step 2: On hot, sunny days, the rate of transpiration is very high. These cells lose water rapidly, losing turgidity. Step 3: This loss of turgidity causes the leaf to roll inward (into a tube shape), thereby reducing the exposed surface area. Step 4: By rolling, fewer stomata are exposed to the environment, significantly reducing further water loss — a xerophytic adaptation. Step 5: They are NOT in guard cells or mesophy