- (a) Parenchyma
- (b) Collenchyma
- (c) Sclerenchyma
- (d) None of the above
Answer:
(a) Parenchyma
Correction made:
Original answer incorrectly marked “None of the above”.
- (a) Parenchyma
- (b) Sclerenchyma
- (c) Collenchyma
- (d) None of the above
Answer:
(b) Sclerenchyma
- (a) Sieve elements
- (b) Vessel elements
- (c) Trichomes
- (d) Guard cells
Answer:
(a) Sieve elements
- (a) Parenchyma
- (b) Collenchyma
- (c) Xylem
- (d) Sclerenchyma
Answer:
(c) Xylem
- (a) Epiphytes
- (b) Hydrophytes
- (c) Halophytes
- (d) Xerophytes
Answer:
(b) Hydrophytes
- (a) Uterus
- (b) Artery
- (c) Vein
- (d) All of the above
Answer:
(d) All of the above
- (a) Axon
- (b) Nerve endings
- (c) Tendons
- (d) Dendrites
Answer:
(c) Tendons
| List I | List II |
|---|---|
| Sclereids | Sclerenchyma |
| Chloroplast | Chlorenchyma |
| Simple tissue | Collenchyma |
| Companion cell | Phloem |
| Tracheids | Xylem |
- Compound epithelium provides mechanical protection to organs.
- Parenchyma, collenchyma and sclerenchyma are simple tissues.
- Xylem and phloem are complex tissues.
- Ciliated epithelial cells are found in the trachea.
- Small intestine lining consists of columnar epithelium.
If false, correct the statement.
True. Epithelial tissue is indeed a protective tissue in animals. It forms the outer covering of the body and lines the internal organs and cavities. The epithelial tissue acts as a barrier against mechanical injury, pathogens, and water loss. Different types of epithelial tissues, such as stratified squamous epithelium in the skin and simple columnar epithelium in the digestive tract, are specifically adapted to provide protection in their respective locations while also performing other functions like absorption and secretion.
False. Bone and cartilage are not areolar connective tissues. They are supportive connective tissues. Areolar connective tissue is a loose connective tissue found beneath the skin and between organs, containing fibroblasts, collagen fibers, and elastic fibers in a gel-like matrix. In contrast, bone is a rigid connective tissue with a mineralized matrix containing calcium and phosphate, while cartilage is a firm but flexible connective tissue with a matrix of collagen fibers and proteoglycans. Both bone and cartilage provide structural support and protection to the body.
True. Parenchyma is a simple tissue. It is composed of living cells with thin cell walls and is found in plants. Parenchyma cells are relatively unspecialized and perform various functions including photosynthesis, storage of food and water, and gas exchange. These cells have the ability to divide and differentiate, making them important for plant growth and repair. Parenchyma tissue is found in leaves, stems, roots, and fruits of plants.
False. Phloem is not made up of tracheids. Phloem consists of sieve tubes, companion cells, phloem fibres, and phloem parenchyma. Sieve tubes are the main conducting elements of phloem, responsible for transporting sugars and other organic compounds throughout the plant. Companion cells are associated with sieve tubes and help regulate their function. Phloem fibres provide mechanical support, while phloem parenchyma stores food. Tracheids, on the other hand, are found in xylem and are involved in water transport.
False. Vessels are not found in collenchyma. Vessels are found in xylem, which is the water-conducting tissue in plants. Collenchyma is a simple supporting tissue composed of living cells with unevenly thickened cell walls, providing mechanical support to young stems and petioles. Xylem contains vessels, tracheids, xylem parenchyma, and xylem fibres, and is responsible for the transport of water and mineral salts from the roots to all parts of the plant.
Answer:
Intercalary meristems are meristematic tissues found between permanent tissues.
They occur:
- at base of leaves
- at base of internodes
Examples:
- Grasses
- Wheat
- Bamboo
- Ginger
Difference from Other Meristems
| Meristem | Location | Function |
|---|---|---|
| Apical meristem | Root and shoot tips | Increase in length |
| Lateral meristem | Sides of stem/root | Increase in thickness |
| Intercalary meristem | Between mature tissues | Regrowth and elongation |
Correction made:
Intercalary meristem mainly helps elongation, not branch production.
Answer:
Complex tissues consist of more than one type of cells working together.
Types:
- Xylem
- Phloem
Answer:
Skeletal muscle is the most abundant muscular tissue.
Functions
- Helps body movement
- Attached to bones
- Voluntary in action
- Multinucleate fibres
Examples:
- Biceps
- Triceps
Answer:
Supporting connective tissue forming endoskeleton is called skeletal connective tissue.
Types:
- Bone
- Cartilage
Functions
- Support body
- Protect organs
- Help locomotion
Answer:
Meiosis reduces chromosome number to half.
Thus:
- gametes become haploid
- fertilization restores diploid condition
This maintains chromosome number across generations.
Chromosomes align at the equatorial plate during metaphase. During this stage of mitosis, each chromosome attaches to spindle fibres through its centromere. The chromosomes are arranged in a single plane at the cell's equator, forming the metaphase plate. This alignment ensures that when the centromeres divide during anaphase, each daughter cell will receive an identical set of chromosomes. The spindle fibres pull the chromosomes to this position, and the cell checkpoint mechanisms ensure that all chromosomes are properly attached before proceeding to the next stage.
# Permanent Tissue
Tissues whose cells have lost power of division are called permanent tissues.
# Types of Simple Permanent Tissues
# (i) Parenchyma
Features
- Living cells
- Thin-walled
- Polygonal or oval
- Intercellular spaces present
Special Types
Aerenchyma
Contains air spaces.
Found in aquatic plants.
Chlorenchyma
Contains chloroplasts.
Performs photosynthesis.
Functions
- Food storage
- Photosynthesis
- Buoyancy
- Secretion
# (ii) Collenchyma
Features
- Living elongated cells
- Unevenly thickened corners
- Non-lignified walls
Function
Provides flexibility and mechanical support.
# (iii) Sclerenchyma
Features
- Dead cells
- Thick lignified walls
- Mechanical strength
Types
Fibres
- Long pointed cells
- Example: Jute
Sclereids
- Broad cells
- Found in fruits and seeds
# Xylem
Conducts water and minerals upward.
Components of Xylem
# (i) Tracheids
- Dead elongated cells
- Thick lignified walls
- Water conduction and support
# (ii) Xylem Fibres
- Long lignified cells
- Provide mechanical support
# (iii) Vessels
- Tube-like dead structures
- Perforated end walls
- Efficient water transport
# (iv) Xylem Parenchyma
- Living cells
- Store starch and fats
| Mitosis | Meiosis |
|---|---|
| Occurs in somatic cells | Occurs in reproductive cells |
| Single division | Two successive divisions |
| Produces 2 daughter cells | Produces 4 daughter cells |
| Daughter cells diploid | Daughter cells haploid |
| Chromosome number maintained | Chromosome number halved |
| Daughter cells identical | Daughter cells genetically different |
Answer:
Platelets help blood clotting.
Without platelets:
- clotting will not occur
- excessive bleeding occurs
- may become fatal
Answer:
Mature red blood cells are not true cells because they lack nucleus.
Correction made:
RBCs possess nucleus only during immature stage.
Observation of Cheek Cells
Observation
- Irregularly shaped cells seen
- Dark-stained nucleus visible
- Cytoplasm lightly stained
Correction made:
Human cheek cells do NOT possess cell wall.
# Important Summary
Meristematic Tissue
Actively dividing tissue.
Types:
- Apical
- Lateral
- Intercalary
Simple Tissues
- Parenchyma
- Collenchyma
- Sclerenchyma
Complex Tissues
- Xylem
- Phloem
Epithelial Tissue
Protective tissue in animals.
Connective Tissue
Provides support and connection.
Muscle Tissue
Responsible for movement.
Nervous Tissue
Conducts impulses.
Mitosis
Growth and repair.
Meiosis
Gamete formation.
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