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Differentiate between meristematic and permanent tissues in plants. 3marks
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Explain the role of apical meristem and lateral meristem in plant growth. 3marks
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What are the functions of xylem and phloem? Describe the components of xylem. 3marks
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Explain the structure and function of collenchyma tissue with a suitable diagram. 3marks
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Describe the different types of epithelial tissues found in animals and their functions. 5marks
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Explain the structure and function of blood as a connective tissue. 3marks
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Differentiate between skeletal muscles, smooth muscles, and cardiac muscles based on their structure and function. 5marks
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Describe the structure of a neuron and its role in the nervous system. 3marks
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Explain the different types of joints found in the human body and their respective movements. 5marks
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How does the skeletal system provide support and protection to the body? 3marks
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Case Study: A student is observing a slide under a microscope and sees cells that are tightly packed, flat, and form a single outer layer. They also observe some cells with hair-like projections.(a) What type of tissue is the student observing? [1 mark](b) Where in the plant would this tissue be found? [1 mark](c) What are the functions of this tissue? 2marks
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Application-Based: During a very hot summer day, a gardener notices that their potted plants are wilting despite regular watering. They decide to increase the amount of water given. However, after a few days, the plants still do not look healthy, and some yellowing of leaves is observed.(a) Which plant tissue is primarily responsible for water transport, and if it's malfunctioning, how might this lead to wilting? [2 marks](b) What other factor related to water transport might be affected by the excessive watering, and which tissue is involved? 2marks
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Diagram Interpretation: Figure 1 shows a T.S. of a plant stem, and Figure 2 shows a T.S. of a plant root.
[Insert simplified diagrams here representing T.S. of stem showing vascular bundles and T.S. of root showing distinct epidermis, cortex, and vascular cylinder]
(a) Identify the vascular tissues in Figure 1 and state their functions. 2marks(b) Identify the tissue responsible for increase in girth of the stem in Figure 1 and explain its location. [2 marks](c) How does the arrangement of vascular tissues differ between Figure 1 and Figure 2, and why is this arrangement significant for their respective functions? [2 marks]
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Situational Analysis: A chef is preparing a meal and accidentally cuts their finger. Immediately, the area starts to bleed, but after a few minutes, a clot forms, and the bleeding stops. Later, the chef notices some redness and swelling around the cut, indicating a mild infection.(a) Which component of blood is responsible for forming the clot? [1 mark](b) What type of blood cells would be attracted to the infected area, and what is their role? 2marks
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Data Interpretation: The table below shows the approximate composition of blood by volume.
| Component | Percentage (%) |
|---|---|
| Plasma | 55 |
| Red Blood Cells | 45 |
| White Blood Cells | <1 |
| Platelets | <1 |
(a) If a person's total blood volume is 5 liters, calculate the volume of plasma. 1mark(b) Explain the function of Red Blood Cells based on the information provided and your knowledge. [2 marks]
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Assertion-Reason:Assertion (A): Epithelial tissues form the outer covering of the body and also line internal organs.Reason (R): Their tightly packed cells with very little intercellular space prevent the entry of germs and reduce water loss.(i) Both (A) and (R) are true, and (R) is the correct explanation of (A).(ii) Both (A) and (R) are true, but (R) is not the correct explanation of (A).(iii) (A) is true, but (R) is false.(iv) (A) is false, but (R) is true. 1mark
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Assertion-Reason:Assertion (A): Involuntary movements, like the beating of the heart, are controlled by skeletal muscles.Reason (R): Skeletal muscles are attached to the skeleton and are responsible for voluntary movements.(i) Both (A) and (R) are true, and (R) is the correct explanation of (A).(ii) Both (A) and (R) are true, but (R) is not the correct explanation of (A).(iii) (A) is true, but (R) is false.(iv) (A) is false, but (R) is true. 1mark
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Conceptual Understanding: You are asked to design a structure that needs to be flexible and strong, yet able to bend without breaking. Which type of simple permanent plant tissue would be most suitable for this purpose, and why? 3marks
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Conceptual Understanding: Why do plant cells have a cell wall, whereas animal cells do not? Explain the functional significance of this difference. 3marks
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Application-Based: Imagine you are helping a farmer diagnose why some of their crops are not growing as tall as expected, even though they are receiving adequate sunlight and water. What two types of plant tissues would you investigate, and what specific issues might you look for in each? 4marks
Answers
1
Meristematic Tissues: These tissues consist of actively dividing cells, are usually small, thin-walled, with dense cytoplasm and a prominent nucleus. They are responsible for plant growth. Examples include apical and lateral meristems.Permanent Tissues: These tissues are derived from meristematic tissues but have lost their ability to divide. Their cells are usually larger, have a definite shape, and may have thickened cell walls. They are specialized for functions like support, protection, or conduction. Examples include parenchyma, sclerenchyma, xylem, and phloem.
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Apical Meristem: Located at the tips of roots and shoots, apical meristems are responsible for the increase in length of the plant, i.e., the growth in height of the stem and depth of the roots.Lateral Meristem: Located along the circumference of stems and roots, lateral meristems are responsible for the increase in girth (thickness) of the plant.
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Functions of Xylem: Transports water and minerals from roots to other parts of the plant; provides mechanical strength to the plant.Functions of Phloem: Transports prepared food (sugars) from leaves to other parts of the plant.Components of Xylem: Tracheids, vessels, xylem parenchyma, and xylem fibres.
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Collenchyma Tissue:Structure: Consists of living cells with unevenly thickened corners due to pectin deposition. The cells are elongated and closely packed. Intercellular spaces are usually absent.Function: Provides mechanical support and flexibility to the plant body, allowing parts like stems and tendrils to bend without breaking.Diagram: A drawing showing elongated cells with thickened corners and thin cell walls.
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Epithelial Tissues:
- Squamous Epithelium: Single layer of thin, flat cells. Found in lining of blood vessels and lungs. Function: Exchange of gases and liquids.
- Cuboidal Epithelium: Cube-shaped cells. Found in ducts of glands and kidney tubules. Function: Secretion and absorption.
- Columnar Epithelium: Tall, pillar-like cells. Found in lining of small intestine. Function: Absorption of nutrients and secretion. May have cilia.
- Ciliated Epithelium: Columnar or cuboidal cells with hair-like cilia on their free surface. Found in respiratory tract. Function: Movement of particles.
- Glandular Epithelium: Modified epithelial cells that secrete substances. Found in salivary glands, sweat glands. Function: Secretion.
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Blood as a Connective Tissue:Structure: Blood is a fluid connective tissue consisting of a liquid matrix called plasma, in which red blood cells, white blood cells, and platelets are suspended. Plasma contains proteins, salts, hormones, and nutrients.Function: Transports nutrients, gases (oxygen and carbon dioxide), hormones, waste products, and antibodies to different parts of the body. It also plays a role in blood clotting and defense against infections.
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Types of Muscles:
- Skeletal Muscles: Attached to bones, responsible for voluntary movements (walking, writing). Cells are long, cylindrical, unbranched, multinucleate, and striated (striped appearance).
- Smooth Muscles: Found in walls of internal organs (stomach, intestine, blood vessels). Responsible for involuntary movements (digestion, blood flow). Cells are spindle-shaped, have a single nucleus, and lack striations.
- Cardiac Muscles: Found only in the heart. Responsible for the rhythmic beating of the heart (involuntary). Cells are cylindrical, branched, have a single nucleus, and are striated. They work continuously without fatigue.
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Neuron (Nerve Cell):Structure: A neuron consists of a cell body (containing the nucleus and cytoplasm), dendrites (branched projections that receive signals), and an axon (a long fibre that transmits signals away from the cell body). The axon terminals transmit signals to other neurons or effectors.Role: Neurons are specialized cells that receive, process, and transmit electrical and chemical signals (nerve impulses) throughout the body, forming the nervous system's communication network. They coordinate body activities, control movements, and enable sensory perception.
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Types of Joints:
- Ball and Socket Joint: Allows movement in all directions (forward, backward, sideways, circular). Example: Shoulder and hip joints.
- Hinge Joint: Allows movement in only one plane (like a door hinge). Example: Elbow and knee joints.
- Pivot Joint: Allows rotation around an axis. Example: Joint between the skull and the first vertebra (neck).
- Fixed Joint: Immovable joints that provide stability. Example: Joints in the skull.
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Skeletal System: The skeletal system is composed of bones and cartilage, forming a framework that provides structural support to the body, enabling it to stand upright. It also protects vital internal organs like the brain, heart, and lungs. The arrangement of bones and joints allows for movement through the action of muscles.
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Case Study:(a) Epithelial tissue. [1 mark](b) This tissue would be found on the outer surface of the plant, such as the epidermis of stems, leaves, and roots. [1 mark](c) Functions: Protection from mechanical injury and infection, reduction of water loss, absorption (e.g., root hairs), and secretion. 2marks
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Application-Based:(a) The primary tissue responsible for water transport is xylem. If the xylem is blocked or damaged (e.g., by waterlogging which can damage root cells involved in water absorption or directly damage xylem vessels), the plant cannot transport sufficient water from the roots to the leaves, leading to wilting. [2 marks](b) Excessive watering can lead to poor aeration of the soil, damaging root cells and impairing water absorption. It can also lead to fungal diseases. The tissue involved in water transport is xylem. If the roots are unhealthy due to waterlogging, even with sufficient water available, the plant won't be able to absorb it effectively. 2marks
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Diagram Interpretation:(a) In Figure 1 (stem T.S.), the vascular tissues are xylem and phloem, usually arranged in vascular bundles. Xylem transports water and minerals upwards, while phloem transports food downwards. [2 marks](b) The lateral meristem is responsible for the increase in girth of the stem. It is located in a ring along the circumference of the stem, between the vascular bundles and the epidermis. [2 marks](c) In the stem (Figure 1), vascular bundles are typically arranged in a ring. In the root (Figure 2), the vascular tissues (xylem and phloem) are arranged radially, with xylem and phloem alternating. This radial arrangement in roots facilitates efficient water and mineral absorption and distribution to all parts of the root. In stems, the ring arrangement supports upward transport to leaves and allows for secondary growth (increase in girth). 2marks
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Situational Analysis:(a) Platelets are responsible for forming the blood clot. [1 mark](b) White Blood Cells (WBCs) would be attracted to the infected area. Their role is to defend the body against infections by engulfing or destroying pathogens. 2marks
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Data Interpretation:(a) Volume of plasma = 55% of 5 liters = 0.55 * 5 L = 2.75 liters. [1 mark](b) Red Blood Cells (RBCs) contain haemoglobin, which binds to oxygen and transports it from the lungs to the body tissues, and carbon dioxide from tissues to the lungs. 2marks
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Assertion-Reason: (i) Both (A) and (R) are true, and (R) is the correct explanation of (A). 1mark
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Assertion-Reason: (iv) (A) is false, but (R) is true. Involuntary movements are controlled by smooth muscles and cardiac muscles, not skeletal muscles. 1mark
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The most suitable tissue would be collenchyma.Explanation: Collenchyma cells have unevenly thickened corners, which provide mechanical support and flexibility. This flexibility allows the tissue to bend without breaking, making it ideal for structures that need to withstand bending forces, such as stems and tendrils, particularly in growing regions. Sclerenchyma, with its thick, lignified walls, is more rigid and brittle, making it suitable for providing hardness and strength (like in seed coats or coconut husks) but not for flexible bending. Living parenchyma, while capable of storage and photosynthesis, lacks the specific structural adaptations for providing significant flexible support. 3marks
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Cell Wall in Plant Cells:Reason: Plant cells have a rigid cell wall made primarily of cellulose outside the cell membrane. Animal cells lack a cell wall.Functional Significance: The cell wall provides structural support and rigidity to the plant cell, helping it maintain its shape and preventing it from bursting when placed in a hypotonic solution (due to turgor pressure). This is crucial for plants as they are generally immobile and need structural integrity. Animal cells, being mobile and surrounded by an extracellular matrix, do not require this rigid outer layer; their flexibility allows for various functions like movement and engulfing particles. 3marks
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Investigation for Crop Height:I would investigate:
1
Meristematic Tissues (Apical Meristems):
- Potential Issues: Lack of division or damage to the apical meristems at the shoot tips could limit vertical growth, resulting in shorter plants. This could be due to genetic factors, nutrient deficiencies, or pest/disease damage at the growing points.
2. Conducting Tissues (Xylem and Phloem): - Potential Issues:
- Xylem: If the xylem is damaged or blocked, water and mineral transport from the roots to the shoot will be inefficient. This will limit the plant's ability to grow tall, as water is essential for cell expansion and photosynthesis.
- Phloem: If the phloem is not effectively transporting food (sugars produced during photosynthesis) from the leaves to the roots and other growing parts, the overall growth and development of the plant, including vertical growth, will be stunted.
[4 marks]
