Q1. How is a pinnately compound leaf different from a palmately compound leaf?

A1.
Both are compound leaves, which means the lamina is divided into smaller parts called leaflets. The difference is in where the leaflets are attached.

  • Pinnately compound leaf

  • Many leaflets are attached along a central axis called the rachis (it acts like the midrib).

  • The leaf looks like a feather.

  • Example: Neem.

  • Palmately compound leaf

  • All the leaflets are attached at one point, at the tip of the petiole.

  • The leaf looks like the fingers of a palm arising from one point.

  • Example: Silk Cotton.

Q2. Explain with suitable examples the different types of phyllotaxy.

A2.
Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. This helps the plant to get proper light and air.

The three main types are:

  1. Alternate phyllotaxy
  • Only one leaf is present at each node.
  • Leaves at successive nodes come on different sides of the stem.
  • Examples: China rose, Mustard, Sunflower.
  1. Opposite phyllotaxy
  • Two leaves arise from the same node, opposite to each other.
  • Examples: Calotropis, Guava.
  1. Whorled phyllotaxy
  • More than two leaves arise from a single node and form a circle or whorl.
  • Example: Alstonia.

Q3. Define the terms (a) aestivation and (b) placentation.

A3.

(a) Aestivation

  • It is the arrangement of sepals or petals in a flower bud before the flower opens.
  • It tells us how they touch or overlap each other in the same whorl.

Common types of aestivation:

  • Valvate: Sepals/petals just touch each other, but do not overlap.
  • Twisted: Each petal overlaps the next one in a regular way (like in China rose).
  • Imbricate: Overlapping is irregular (no fixed pattern).
  • Vexillary (papilionaceous): One large standard petal, two wing petals and two keel petals (as in pea).

(b) Placentation

  • It is the arrangement of ovules inside the ovary.
  • It shows where the ovules are attached to the ovary wall or to a central axis (placenta).

Q4. Differentiate between Racemose and Cymose inflorescence.

A4.
Inflorescence is the arrangement of flowers on the floral axis.

Feature Racemose Inflorescence Cymose Inflorescence
Growth of main axis Main axis keeps growing for a long time (indeterminate). Main axis stops growing after forming a flower (determinate).
Order of opening of flowers Flowers open in acropetal succession – older flowers at the bottom, younger at the top. Flowers open in basipetal succession – older flowers near the top/center, younger towards the base.
Examples Mustard, Radish, Gulmohar Jasmine, Bougainvillea

Q5. Describe the structure of a dicot (gram) seed.

A5.
A gram seed is a typical dicotyledonous seed, so it has two cotyledons.

Main parts:

  1. Seed coat
  • Outer protective covering of the seed.
  • Has two layers:
    • Testa: Outer, tough and brown.
    • Tegmen: Inner, thin layer.
  • You can see:
    • Hilum: Scar where the seed was attached to the fruit.
    • Micropyle: Small pore just above the hilum through which water enters during germination.
  1. Embryo
  • Present inside the seed coat.
  • Consists of:
    • Embryonal axis: The central line of the embryo.
    • Cotyledons (2): Large, fleshy seed leaves that store food.
    • Radicle: Lower end of the axis – develops into the root.
    • Plumule: Upper end of the axis – develops into the shoot.

Q6. Describe the structure of a monocot (maize) seed.

A6.
A maize grain is a monocot seed and also a fruit, because the seed coat is fused with the fruit wall.

Main parts:

  1. Seed coat and fruit wall
  • Thin and membranous.
  • Seed coat and pericarp are fused, so they cannot be separated easily.
  1. Endosperm
  • Makes up the major part of the seed.
  • Stores starch (food).
  • Outside is a protein-rich layer called the aleurone layer.
  1. Embryo
  • Lies in a small groove on one side of the endosperm.
  • Consists of:
    • Scutellum: Single, shield-shaped cotyledon.
    • Plumule: Baby shoot, protected by a sheath called coleoptile.
    • Radicle: Baby root, protected by a sheath called coleorhiza.

Q7. Write the floral formula for the Solanaceae family.

A7.
The floral formula for Solanaceae (potato, tomato, brinjal family) is:

⊕ ⚥ K(₅) C(₅) A₅ G(₂)

Meaning of symbols:

  • ⊕ : Flower is actinomorphic – radially symmetrical.
  • ⚥ : Flower is bisexual – both androecium and gynoecium present.
  • K(₅) : Calyx has 5 sepals, fused (gamosepalous).
  • C(₅) : Corolla has 5 petals, fused (gamopetalous).
  • A₅ : Androecium has 5 stamens, usually epipetalous (attached to petals).
  • G(₂) : Gynoecium has 2 fused carpels (bicarpellary, syncarpous), with a superior ovary, usually bilocular with axile placentation.

Q8. Describe the various types of placentations found in flowering plants.

A8.
Placentation is the pattern in which ovules are attached inside the ovary. Main types:

  1. Marginal placentation
  • Ovules are arranged along the margin of a single carpel.
  • They form one row on one side.
  • Example: Pea.
  1. Axile placentation
  • Ovary is multilocular (has many chambers).
  • Ovules are attached to a central axis.
  • Examples: Tomato, Lemon, China rose.
  1. Parietal placentation
  • Ovules are attached to the inner wall of the ovary.
  • Sometimes a false septum forms and divides the ovary into chambers.
  • Examples: Mustard, Argemone.
  1. Free-central placentation
  • Ovules are attached to a central column, but no septa are present (ovary unilocular).
  • Examples: Primrose, Dianthus.
  1. Basal placentation
  • A single ovule is attached at the base of the ovary.
  • Examples: Sunflower, Marigold.

Q9. Describe the arrangement of floral members in relation to their insertion on thalamus (Ovary Position).

A9.
According to the position of ovary on the thalamus and the position of other floral parts, flowers are of three types:

  1. Hypogynous flower (superior ovary)
  • Ovary is at the highest position.
  • Sepals, petals and stamens arise from below the ovary.
  • Ovary is superior.
  • Examples: Mustard, China rose, Brinjal.
  1. Perigynous flower (half-inferior ovary)
  • Thalamus becomes cup-shaped.
  • Ovary lies in the center of the cup.
  • Other floral parts arise from the rim of the cup.
  • Ovary is half-inferior.
  • Examples: Plum, Rose, Peach.
  1. Epigynous flower (inferior ovary)
  • Thalamus grows upwards and completely encloses the ovary and fuses with it.
  • Other floral parts appear to arise from the top of the ovary.
  • Ovary is inferior.
  • Examples: Guava, Cucumber, Sunflower (ray florets).

Q10. Differentiate between a false fruit and a parthenocarpic fruit.

A10.

  • False fruit

  • A fruit in which, along with the ovary, other floral parts (like thalamus, sepals or petals) also take part in forming the fruit.

  • It develops after normal fertilization.

  • It generally has seeds.

  • Examples: Apple, Strawberry, Cashew.

  • Parthenocarpic fruit

  • A fruit that develops without fertilization.

  • Because fertilization does not occur, the fruit is usually seedless.

  • It may occur naturally or can be induced by plant hormones.

  • Example: Banana.

Q11. Differentiate between a rhizome and a tuber, both modified for storage.

A11.
Both rhizome and tuber are underground stem modifications used for food storage and vegetative reproduction, but they are structurally different.

  • Rhizome

  • A horizontal, fleshy underground stem.

  • Shows nodes and internodes.

  • Bears scaly leaves and buds at nodes.

  • Roots and new shoots arise from the nodes.

  • Examples: Ginger, Turmeric.

  • Tuber

  • A swollen end of an underground stem or branch.

  • Has “eyes”, which are actually axillary buds.

  • Nodes and internodes are not very clear externally.

  • Example: Potato.

Q12. Differentiate between a stem tendril and a leaf tendril.

A12.
Both stem tendrils and leaf tendrils are thin, coiled structures that help plants climb and get support, but they come from different organs.

  • Stem tendril

  • A modified stem.

  • Usually develops from an axillary bud.

  • Seen in plants with weak stems.

  • Examples: Gourds (Cucumber, Pumpkin), Grapevine.

  • Leaf tendril

  • A modified leaf or part of a leaf (like leaflets or the petiole).

  • Does not arise from a stem bud.

  • Example: Pea – upper leaflets are modified into tendrils.

Q13. What are pneumatophores? What is their function?

A13.

  • What are pneumatophores?
    Pneumatophores are special breathing roots found in plants growing in swampy, waterlogged, salty soils (mangroves).

  • How do they grow?
    Unlike normal roots, they grow upwards, out of the soil (they are negatively geotropic).

  • Function:
    The exposed part of pneumatophores has many small openings called lenticels. These lenticels allow air (oxygen) to enter, helping in respiration when the soil has very little oxygen.

  • Example:
    Rhizophora and other mangrove plants.

Q14.List the four whorls of a flower and their functions.

A14.

Calyx (protection), Corolla (attraction), Androecium (male reproductive), Gynoecium (female reproductive).

Q15. What is a drupe? Describe its parts in a mango and a coconut.

A15.

Drupe – definition

  • A drupe is a simple, fleshy fruit that usually develops from a single (monocarpellary) superior ovary and is mostly one-seeded.
  • Its fruit wall (pericarp) has three layers:
  • Epicarp – outer skin
  • Mesocarp – middle fleshy or fibrous part
  • Endocarp – inner hard, stony layer

Drupe example – Mango

  • Epicarp: Thin, smooth outer skin of the mango.
  • Mesocarp: The thick, fleshy, sweet part that we eat.
  • Endocarp: The hard, stony shell around the seed.

Drupe example – Coconut

  • Epicarp: Thin outer green or brown skin.
  • Mesocarp: Thick fibrous layer (coir).
  • Endocarp: Hard, stony shell around the edible kernel and coconut water.