TS Intermediate Botany 1st Year Model Paper 2024

 

SECTION – A

Note :- (i) Answer ALL questions. (ii) Each question carries TWO marks. (iii) All are very short answer type questions.

1. Give the scientific name of Mango. Identify the generic name and specific epithet.

Answer:
The scientific name of Mango is Mangifera indica.

  • Generic name: Mangifera
  • Specific epithet: indica

2. How are Viroids different from Viruses?

Answer:

  • Viroids are small, circular RNA molecules that lack a protein coat. They cause diseases in plants.
  • Viruses, on the other hand, consist of either DNA or RNA enclosed in a protein coat, and they can infect both plants and animals. Unlike viroids, viruses require a host cell for replication.

3. Who discovered the cell and what was the book written by him?

Answer:
The cell was discovered by Robert Hooke in 1665. He published his findings in the book titled “Micrographia”.

4. What is meant by pulvinus leaf base? In members of which angiospermic family do you find them?

Answer:
The pulvinus is a swollen, specialized region at the base of the leaf stalk or petiole that helps in leaf movements, such as folding or bending.
It is found in the Leguminosae (Fabaceae) family.

5. What is the morphology of the cup-like structure in Cyathium? In which family is it found?

Answer:
In Cyathium, the cup-like structure is an involucre, which is made up of bracts that form a cup shape surrounding the male and female reproductive organs.
This structure is found in the Euphorbiaceae family.

6. Name the type of pollination mechanism found in members of Fabaceae.

Answer:
Members of the Fabaceae family primarily undergo insect pollination (entomophily).

7. What is the feature of a metacentric chromosome?

Answer:
A metacentric chromosome has its centromere located in the middle, resulting in two arms of equal length.

8. Give one example for each of amino acids, sugars, nucleotides, and fatty acids.

Answer:

  • Amino acid: Glycine
  • Sugar: Glucose
  • Nucleotide: Adenine
  • Fatty acid: Oleic acid

9. An anther has 1200 pollen grains. How many pollen mother cells must have been there to produce them?

Answer:
Each pollen mother cell (PMC) produces 4 pollen grains.
To produce 1200 pollen grains, the number of PMCs required = 1200 / 4 = 300 PMCs.

10. Define Heliophytes and Sciophytes. Name a plant from your locality that is either Heliophytes or Sciophytes.

Answer:

  • Heliophytes are plants that thrive in bright sunlight.
  • Sciophytes are plants that grow in shade or under low light conditions.

Example from locality:

  • Heliophyte: Sunflower (needs direct sunlight to grow)
  • Sciophyte: Fern (grows well in shady areas)

 

SECTION – B

(i) Answer ANY SIX questions. (ii) Each question carries FOUR marks. (iii) All are short answer type questions. (iv) Draw labelled diagrams, wherever necessary.

11. Give a brief account of Dinoflagellates.

Answer:
Dinoflagellates are unicellular, eukaryotic organisms that belong to the group Dinoflagellata. They are primarily found in marine and freshwater environments, and some species are bioluminescent. Dinoflagellates have two flagella: one is used for propulsion, and the other is used for steering. Many dinoflagellates are photosynthetic, but some are heterotrophic or mixotrophic. Certain dinoflagellates can cause red tides, which can produce toxins harmful to marine life and humans. They play a vital role in the marine food chain and contribute to primary production in aquatic ecosystems.

12. How would you distinguish monocots from dicots?

Answer:
Monocots and dicots are two classes of angiosperms, and they can be distinguished by the following features:

  • Monocots:

    • One cotyledon (seed leaf).
    • Parallel venation in leaves.
    • Floral parts usually in multiples of 3.
    • Vascular bundles scattered throughout the stem.
    • Fibrous root system.

  • Dicots:

    • Two cotyledons.
    • Reticulate venation in leaves.
    • Floral parts typically in multiples of 4 or 5.
    • Vascular bundles arranged in a circle or ring in the stem.
    • Tap root system.

13. Distinguish between asexual and sexual reproduction. Why is vegetative reproduction also considered a type of asexual reproduction?

Answer:

  • Asexual reproduction involves a single parent and results in offspring that are genetically identical to the parent. Common methods include binary fission, budding, and vegetative reproduction.
  • Sexual reproduction involves the fusion of male and female gametes (sperm and egg), resulting in offspring that have a combination of genetic material from both parents, leading to genetic diversity.

Vegetative reproduction is considered a type of asexual reproduction because it occurs without the involvement of gametes or fertilization. New plants arise from vegetative parts like stems, roots, or leaves, producing offspring that are genetically identical to the parent plant.

14. Describe the essential floral parts of plants belonging to Liliaceae.

Answer:
The essential floral parts of plants belonging to the Liliaceae family (e.g., lilies, tulips) are:

  • Sepals: Usually 3, they form the outermost whorl and protect the flower bud before it blooms.
  • Petals: Also 3, the petals are typically large, colorful, and serve to attract pollinators.
  • Stamens: 6 stamens (in two whorls of 3), which are the male reproductive organs consisting of an anther (pollen-producing part) and a filament (stalk).
  • Pistil: The female reproductive part consisting of a stigma, style, and ovary. The ovary contains ovules that develop into seeds after fertilization.

15. Differentiate between Rough Endoplasmic Reticulum (RER) and Smooth Endoplasmic Reticulum (SER).

Answer:

  • Rough Endoplasmic Reticulum (RER):

    • Contains ribosomes on its surface, giving it a “rough” appearance.
    • Primarily involved in the synthesis and modification of proteins.
    • Proteins synthesized here are often destined for secretion or for incorporation into membranes.

  • Smooth Endoplasmic Reticulum (SER):

    • Lacks ribosomes on its surface, giving it a smooth appearance.
    • Involved in the synthesis of lipids, steroids, and phospholipids.
    • Plays a role in detoxification and the metabolism of carbohydrates.

16. Explain Prophase-I of meiosis.

Answer:
Prophase-I of meiosis is the first and longest phase of meiosis I. It consists of several key events:

  1. Chromosome Condensation: Chromosomes become visible under a microscope as they condense.
  2. Synapsis: Homologous chromosomes pair up through a process called synapsis, forming a structure known as a tetrad (four chromatids).
  3. Crossing Over: Homologous chromosomes exchange segments of chromatids at points called chiasmata. This process leads to genetic recombination, increasing genetic diversity.
  4. Spindle Formation: A mitotic spindle begins to form, which will help segregate chromosomes during later stages of meiosis.
  5. Disappearance of the Nuclear Envelope: The nuclear envelope begins to break down, allowing the spindle fibers to access the chromosomes.

17. State the location and function of different types of meristems.

Answer:
Meristems are regions of active cell division in plants that are responsible for growth. There are three main types of meristems:

  • Apical Meristem:

    • Location: Found at the tips of stems and roots.
    • Function: Responsible for primary growth, leading to the elongation of the plant and the formation of new tissues.

  • Lateral Meristem:

    • Location: Found along the sides of stems and roots, in the form of vascular cambium and cork cambium.
    • Function: Responsible for secondary growth, resulting in an increase in the girth (width) of the plant.

  • Intercalary Meristem:

    • Location: Found at the base of leaves or internodes (especially in monocots).
    • Function: Responsible for the regrowth and elongation of plant parts, such as leaves and stems.

18. Enumerate the morphological adaptations of xerophytes.

Answer:
Xerophytes are plants adapted to survive in dry environments. Their morphological adaptations include:

  • Reduced Leaf Surface Area: Xerophytes often have small or needle-like leaves to minimize water loss.
  • Thick, Waxy Cuticle: The leaves and stems have a thick cuticle that helps prevent water loss.
  • Sunken Stomata: Stomata are located in depressions or pits to reduce evaporation.
  • Succulent Tissues: Some xerophytes store water in specialized tissues, such as cacti, which have fleshy stems.
  • Deep or Extensive Root Systems: Xerophytes may have deep roots that reach underground water sources or wide-spreading roots to collect water from a larger area.
  • Leaf Modifications: In some xerophytes, leaves are modified into spines to further reduce water loss.
  • Dormancy: Some xerophytes can enter a dormant state during periods of extreme drought, resuming growth when water is available.

SECTION-C

(i) Answer ANY TWO questions. (ii) Each question carries EIGHT marks. (iii) All are long answer type questions. (iv) Draw labelled diagrams, wherever necessary.

18. Explain, how stem is modified variously to perform different functions?

Answer:
The stem in plants can be modified in various ways to perform functions other than its primary role of support and conduction of water, minerals, and nutrients. Some of the main modifications of the stem include:

  1. Tendrils:

    • Function: Used for climbing in plants like pea or grapevine, helping the plant to attach to a support and grow in a better environment.
    • Example: Pea plant has modified stems in the form of tendrils.

  2. Thorns:

    • Function: Provide defense against herbivores.
    • Example: Bougainvillea has thorns on its stems.

  3. Succulent Stems:

    • Function: Store water in dry conditions.
    • Example: Cactus has modified stems that store water to survive in arid climates.

  4. Flattened Stems (Phylloclades):

    • Function: Perform photosynthesis when leaves are reduced or absent.
    • Example: Opuntia (a type of cactus) has flattened stems that act as photosynthetic organs.

  5. Stolons or Runners:

    • Function: Vegetative reproduction by growing horizontally above ground.
    • Example: Strawberry plant uses runners to propagate.

  6. Bulbs:

    • Function: Store food and help in vegetative reproduction.
    • Example: Onion and garlic have bulbs which are modified stems that store food.

  7. Rhizomes:

    • Function: Serve for vegetative reproduction and store food.
    • Example: Ginger has rhizomes that help in vegetative propagation.

  8. CORMs:

    • Function: Serve as storage organs for food and water, as well as for vegetative propagation.
    • Example: Taro and Gladiolus use corms for vegetative reproduction.

19. With a neat labelled diagram, describe the parts of a mature angiosperm embryo sac. Mention the role of synergids.

Answer:
The mature angiosperm embryo sac (also known as the female gametophyte) is located within the ovule and consists of the following parts:

  • Egg Cell: Located at the center of the embryo sac and ready to fuse with the male gamete (sperm).
  • Synergids: These are two cells located near the egg cell at the micropylar end. They play a vital role in guiding the pollen tube towards the egg cell and facilitate the entry of the male gamete.
  • Antipodal Cells: These are three cells located at the opposite end of the embryo sac (away from the micropyle) and are involved in nourishing the developing embryo.
  • Central Cell: Contains two polar nuclei that fuse with the male gamete during fertilization to form the triploid endosperm.
  • Micropyle: A small opening in the ovule through which the pollen tube enters.

Role of Synergids:
Synergids are essential for guiding the pollen tube toward the egg. They secrete certain chemicals that attract the pollen tube, ensuring that it reaches the egg for successful fertilization. They play a key role in the process of fertilization, as they help in the reception of the male gametes.

Diagram:
(Include a labeled diagram showing the egg cell, synergids, antipodal cells, central cell, and micropyle in the ovule. The diagram would typically look like an oval shape with the micropyle at one end.)

20. Describe the internal structure of a monocot root.

Answer:
The internal structure of a monocot root is characterized by several distinctive features:

  1. Epidermis:

    • The outermost layer of the root, which is made up of a single layer of cells. It protects the root and is responsible for the absorption of water and minerals.

  2. Cortex:

    • Located beneath the epidermis, the cortex consists of parenchyma cells that store food. It also contains the endodermis, which regulates the flow of water and nutrients into the vascular bundle.

  3. Endodermis:

    • The innermost layer of the cortex. The cells here are tightly packed and contain the Casparian strip, which prevents the backflow of water and forces water to pass through the plasma membranes of the cells, ensuring selective absorption of minerals.

  4. Vascular Bundle:

    • In monocot roots, the vascular bundles are arranged in a circle around the central pith. The vascular bundle consists of:
      • Xylem: Conducts water and minerals from the roots to the rest of the plant.
      • Phloem: Transports food (sugars) produced during photosynthesis.
      • Pericycle: A layer of cells just inside the endodermis, from which lateral roots arise.

  5. Pith:

    • The central portion of the monocot root, consisting of parenchyma cells that store food and water.

  6. Root Cap:

    • The root cap is the protective covering at the tip of the root. It helps in protecting the growing root tip from mechanical injury as it pushes through the soil.

21. Explain how stem is modified variously to perform different functions?

Answer:
The stem in plants can be modified to serve various functions beyond its primary role of support and conduction. These modifications help plants adapt to their environments. Some common modifications include:

  1. Tendrils:

    • Function: Climbing and support.
    • Example: Pea plant uses tendrils for climbing.

  2. Thorns:

    • Function: Protection from herbivores.
    • Example: Bougainvillea and Citrus have thorns to protect themselves.

  3. Succulent Stems:

    • Function: Store water.
    • Example: Cactus has a thick, fleshy stem that stores water in dry climates.

  4. Phylloclades (Flattened Stems):

    • Function: Photosynthesis, especially when leaves are reduced or absent.
    • Example: Opuntia (cactus) has flattened stems performing photosynthesis.

  5. Stolons (Runners):

    • Function: Vegetative reproduction.
    • Example: Strawberry plant sends out runners that develop into new plants.

  6. Bulbs:

    • Function: Store food and facilitate vegetative reproduction.
    • Example: Onion and Garlic.

  7. Rhizomes:

    • Function: Store food and provide vegetative reproduction.
    • Example: Ginger and Turmeric use rhizomes to propagate.

  8. Corms:

    • Function: Storage of food and water, aiding in vegetative reproduction.
    • Example: Gladiolus and Taro.

Each of these modifications helps plants adapt to their surroundings by performing additional roles such as protection, reproduction, water storage, and photosynthesis.