All questions of Tissues for Grade 10 Exam

Overview of Rutherford’s Experiment
Rutherford’s alpha particle scattering experiment, conducted in 1909, was pivotal in shaping our understanding of atomic structure. The experiment involved firing alpha particles at a thin gold foil and observing their scattering patterns.
Key Findings
- Alpha Particles: These are positively charged particles emitted from radioactive materials.
- Gold Foil: A very thin sheet of gold was used, allowing alpha particles to pass through with minimal obstruction.
- Detection Screen: A fluorescent screen encircled the foil to detect scattered alpha particles.
Observations
- Most alpha particles passed straight through the foil, indicating that atoms are largely empty space.
- A small fraction of alpha particles were deflected at large angles, while a very few even bounced back, suggesting a dense core.
Conclusion: Discovery of the Nucleus
- Dense Core: The unexpected deflections led Rutherford to conclude that a small, dense, positively charged region existed within the atom, which he termed the nucleus.
- Size and Charge: The nucleus was found to be much smaller than the atom itself, containing most of the atom’s mass.
Impact on Atomic Theory
- Rutherford’s findings led to the downfall of the plum pudding model and paved the way for the modern understanding of atomic structure, where electrons orbit a central nucleus containing protons and neutrons.
In summary, Rutherford's alpha particle scattering experiment was crucial in identifying the nucleus, fundamentally altering the perspective on atomic structure and leading to the development of modern atomic theory.

Division of Labour

The presence of tissues in a multicellular organism ensures division of labour. Division of labour refers to the specialization of different cells or groups of cells to perform specific functions within an organism. This specialization allows the organism to carry out various complex tasks efficiently and effectively.

Explanation:

What are tissues?
Tissues are groups of similar cells that work together to perform a specific function. In multicellular organisms, tissues are organized into organs, and organs work together to form organ systems. This hierarchical organization allows for the division of labour among different cells and tissues.

Specialized functions
Different tissues have specialized functions in the body. For example, muscle tissues are responsible for movement, nervous tissues transmit signals and coordinate body functions, and epithelial tissues form protective coverings and linings. Each tissue type is specialized to perform a specific function, contributing to the overall functioning of the organism.

Efficient functioning
The division of labour among different tissues allows for efficient functioning of the organism. Each tissue focuses on its specific task, optimizing its structure and function to perform that task. This specialization ensures that the organism can carry out complex processes more effectively, such as digestion, respiration, circulation, and reproduction.

Coordination and regulation
The presence of tissues also enables better coordination and regulation within the organism. Different tissues communicate and interact with each other, allowing for the integration of various physiological processes. For example, the nervous tissue coordinates the activities of different tissues and organs through electrical signals, while the endocrine tissue releases hormones that regulate body functions.

Overall functioning
The division of labour among tissues ensures that all the necessary functions for the survival and well-being of the organism are carried out efficiently. Each tissue contributes its specialized function, and together they work in harmony to maintain homeostasis and support the overall functioning of the organism.

In conclusion, the presence of tissues in a multicellular organism ensures division of labour. This division allows for specialization, efficient functioning, coordination, and regulation among different tissues, ultimately contributing to the overall well-being and survival of the organism.

Understanding Anions
An anion is a negatively charged ion formed when an atom gains electrons. The ability of an element to form anions is largely influenced by its position in the periodic table, particularly its electronegativity and the number of valence electrons.
Elements and Their Proton Counts
- W: 8 protons (Oxygen)
- X: 11 protons (Sodium)
- Y: 9 protons (Fluorine)
- Z: 17 protons (Chlorine)
Analysis of Each Element
- Element W (Oxygen):
- Has 6 valence electrons.
- Can gain 2 electrons to achieve a stable octet.
- Can form anions (O^2-).
- Element X (Sodium):
- Has 1 valence electron.
- Tends to lose this electron to achieve stability.
- Cannot form anions; instead, it forms cations (Na^+).
- Element Y (Fluorine):
- Has 7 valence electrons.
- Can gain 1 electron to achieve a stable octet.
- Can form anions (F^-).
- Element Z (Chlorine):
- Has 7 valence electrons.
- Can gain 1 electron to achieve a stable octet.
- Can form anions (Cl^-).
Conclusion
Among the elements listed, Element X (Sodium) is the one that cannot form an anion because it prefers to lose its single valence electron, making it a cation instead. All other elements can gain electrons to form stable anions. Hence, the correct answer is option 'A'.

Chlorenchyma is a type of parenchyma tissue that contains chlorophyll. Chloroplasts are the cellular organelles that contain chlorophyll, which is responsible for the green color of plants and their ability to carry out photosynthesis. Chlorenchyma cells are found in the leaves of plants and are primarily responsible for photosynthesis.

Chlorenchyma cells have several unique characteristics that make them well-suited for their role in photosynthesis:

1. Presence of chloroplasts: Chlorenchyma cells contain numerous chloroplasts, which are responsible for capturing light energy and converting it into chemical energy through photosynthesis. Chloroplasts contain chlorophyll pigments that absorb light energy, allowing plants to produce glucose and oxygen.

2. Thin cell walls: Chlorenchyma cells have thin and flexible cell walls, which allow for efficient gas exchange and the movement of substances in and out of the cell. This is important for the uptake of carbon dioxide and the release of oxygen during photosynthesis.

3. Large intercellular spaces: Chlorenchyma cells are loosely packed, creating large intercellular spaces between them. These spaces allow for the diffusion of gases, such as carbon dioxide and oxygen, within the leaf, ensuring that chloroplasts have access to an adequate supply of carbon dioxide for photosynthesis and can release oxygen as a byproduct.

4. Irregular shape: Chlorenchyma cells often have irregular shapes with many interdigitations and extensions. This provides a large surface area for the absorption of light energy and enhances the efficiency of photosynthesis.

Overall, the presence of chloroplasts and the unique structural characteristics of chlorenchyma cells make them specialized for photosynthesis. They play a crucial role in capturing light energy, converting it into chemical energy, and producing glucose and oxygen, which are essential for the survival and growth of plants.

Understanding Valency
Valency refers to the combining capacity of an element, determined by the number of electrons an atom can lose, gain, or share to form a compound. Elements with a valency of one are versatile in their ability to bond with others.
Elements with Valency One
- Metals: Some metals, like sodium (Na) and potassium (K), have a valency of one. They tend to lose one electron to achieve a stable electronic configuration, forming positive ions (cations).
- Non-Metals: Non-metals such as chlorine (Cl) and fluorine (F) also exhibit a valency of one. These elements gain an electron to complete their outer shell, forming negative ions (anions).
- Metalloids: Metalloids can have variable valency, but they do not predominantly exhibit a valency of one.
Conclusion
The key takeaway is that elements with a valency of one can be either metals or non-metals. This dual nature highlights the diversity of chemical behavior in the periodic table. Therefore, the correct answer is option 'D,' as it acknowledges that both categories can exhibit a valency of one. Understanding these distinctions is crucial in grasping the fundamental concepts of chemistry.

Role of Sieve Tubes in Plants
Sieve tubes are an essential component of the phloem, the vascular tissue responsible for transporting nutrients in plants. Their primary function is to facilitate the movement of food materials, particularly sugars produced through photosynthesis.
Structure of Sieve Tubes
- Sieve tubes are made up of elongated cells called sieve elements.
- These cells are connected end-to-end, forming long tubes.
- The end walls of these cells have sieve plates, which contain pores that allow for the flow of substances.
Transporting Food Materials
- Sieve tubes primarily transport organic compounds, including sugars, amino acids, and hormones.
- The transportation occurs from source tissues (like leaves) where photosynthesis takes place to sink tissues (like roots and fruits) where these nutrients are utilized or stored.
- This movement is achieved through a process called translocation, which relies on pressure differences within the sieve tubes.
Importance of Translocation
- Translocation is vital for plant growth and development as it ensures that all parts of the plant receive the necessary nutrients.
- The nutrients transported by sieve tubes support various functions, including energy production, growth, and reproduction.
Conclusion
In summary, the primary role of sieve tubes in plants is to transport food materials, making them crucial for the plant's overall health and growth. Without sieve tubes, plants would struggle to distribute the nutrients essential for their survival.

Sprain is caused by excessive pulling of Ligaments.

Ligaments are tough, fibrous bands of tissue that connect bones to other bones in a joint. They provide stability and support to the joint, preventing excessive movement and maintaining proper alignment. When a ligament is stretched or torn due to excessive force or overstretching, it is called a sprain.

Excessive pulling of ligaments can occur due to various reasons, including:

1. Trauma or injury: Sprains are commonly caused by sudden twisting or bending movements that put excessive stress on the ligaments. This can happen during sports activities, accidents, or falls.

2. Overuse or repetitive stress: Continuous repetitive movements or overuse of a joint can lead to ligament sprains. This is common in athletes or individuals who engage in repetitive activities that strain the ligaments, such as running, jumping, or repetitive motions involved in certain sports or occupations.

3. Weak or imbalanced muscles: Weakness or imbalances in the muscles surrounding a joint can also contribute to ligament sprains. When the muscles are not able to provide adequate support and stability, the ligaments may be more prone to injury.

Sprains can range from mild to severe, depending on the extent of ligament damage. Mild sprains involve stretching or minor tearing of the ligament fibers, while severe sprains involve complete tears or ruptures of the ligament.

Common symptoms of a sprain include pain, swelling, bruising, limited range of motion, and instability in the affected joint. Treatment for a sprain typically involves the RICE method: Rest, Ice, Compression, and Elevation. Resting the injured joint, applying ice to reduce swelling, using compression bandages to support the joint, and elevating the limb can help alleviate symptoms and promote healing.

In severe cases, medical intervention may be required, such as immobilization with a brace or cast, physical therapy, or, in rare cases, surgical repair of the ligament.

In conclusion, sprains are caused by excessive pulling of ligaments, which can occur due to trauma, overuse, or weakness in the surrounding muscles. Prompt and appropriate treatment is important to ensure proper healing and prevent long-term complications.