CBSE Class 7 Science Chapter 11: Transportation in Animals and Plants NCERT Solutions

Solution: The correct matching of structures with their functions is as follows:

• (i) Stomata - (b) Transpiration: Stomata are pores on leaves that allow for the release of water vapor.
• (ii) Xylem - (d) Transport of water: Xylem is the vascular tissue responsible for transporting water and dissolved minerals from the roots to the rest of the plant.
• (iii) Root hairs - (a) Absorption of water: Root hairs are tiny extensions of root epidermal cells that significantly increase the surface area for absorbing water and minerals from the soil.
• (iv) Phloem - (c) Transport of food: Phloem is the vascular tissue that transports sugars (food) produced during photosynthesis from the leaves to other parts of the plant where they are needed for growth or storage.

(Note: Option (e) Synthesis of carbohydrates is primarily done by leaves through photosynthesis and is not a direct function of any of the listed structures in terms of transport or absorption.)

Solution: Here are the completed sentences:

1. The blood from the heart is transported to all parts of the body by the arteries. Arteries carry oxygenated blood away from the heart.
2. Haemoglobin is present in red blood cells. Haemoglobin is the protein that carries oxygen.
3. Arteries and veins are joined by a network of capillaries. These are tiny vessels where exchange of substances occurs.
4. The rhythmic expansion and contraction of the heart is called heartbeat. This process pumps blood throughout the body.
5. The main excretory product in human beings is urea. Urea is a waste product filtered by the kidneys.
6. Sweat contains water and salt. Sweat helps in regulating body temperature.
7. Kidneys eliminate the waste materials in the liquid form called urine. Urine is composed of water, urea, and other waste salts.
8. Water reaches great heights in the trees because of suction pull caused by transpiration. Transpiration is the process of water loss from leaves, creating a pull that draws water up from the roots.

Solution:

(a) In plants, water is transported through (i) xylem. Xylem is the specialized tissue responsible for the upward movement of water and minerals from the roots to the leaves.

(b) Water absorption through roots can be increased by keeping the plants (iii) under the fan. Placing a plant under a fan increases air movement, which enhances transpiration. Increased transpiration creates a stronger transpiration pull, thereby increasing the rate of water absorption by the roots from the soil.

Solution: The transport of materials is essential for both plants and animals because:

• Supply of Nutrients and Oxygen: All cells in an organism require a continuous supply of nutrients and oxygen to perform metabolic activities, generate energy, and carry out life processes. The transport system ensures these vital substances reach every cell.
• Removal of Waste Products: Metabolic activities produce waste products, such as carbon dioxide and urea. If these wastes accumulate, they can become toxic. The transport system collects these wastes from the cells and carries them to the organs responsible for their elimination (e.g., lungs for CO2, kidneys for urea).
• Hormone Distribution: In animals, hormones produced by endocrine glands are transported via the blood to target organs, regulating various bodily functions.
• Water and Mineral Transport in Plants: Plants need to transport water and minerals absorbed by the roots to the leaves for photosynthesis, and the food produced in the leaves needs to be transported to all other parts for growth and energy.

In summary, the transport system is vital for maintaining homeostasis, enabling growth, and ensuring the survival of the organism by facilitating the exchange of necessary substances and the removal of harmful wastes.

Solution: If there are no platelets in the blood, the most significant consequence would be the inability of the blood to clot properly. Platelets are small, irregular-shaped cell fragments that play a critical role in hemostasis, the process of stopping bleeding. When a blood vessel is injured, platelets gather at the site of injury and form a plug, initiating the clotting cascade. Without platelets, this process would not occur effectively. Consequently, even minor injuries could lead to excessive and prolonged bleeding (hemorrhage), potentially resulting in severe blood loss, shock, and even death.

Solution: Stomata (singular: stoma) are tiny pores, typically found on the surface of leaves, and sometimes on stems. Each stoma is surrounded by a pair of specialized cells called guard cells, which regulate the opening and closing of the pore.

The two main functions of stomata are:

1. Gas Exchange: Stomata facilitate the exchange of gases between the plant and the atmosphere. They allow carbon dioxide (CO2) to enter the leaf for photosynthesis and enable oxygen (O2), a byproduct of photosynthesis, to be released.
2. Transpiration: Stomata are the primary sites for transpiration, which is the process of water vapor being released from the plant into the atmosphere. This process helps in the upward movement of water from the roots to the leaves (transpiration pull) and also aids in cooling the plant.