Science Worksheet (Set 15)
Topic: Transport in Animals and Plants
Grade: VII
Q1. Answer briefly:
a. How do plants excrete waste products?
– Plants excrete waste through stomata (gas exchange), lenticels (in woody plants), and through the process of transpiration.
– Some plants store waste in leaves, bark, or fruits, which later shed.
– Some plants store waste in leaves, bark, or fruits, which later shed.
b. Each kidney contains about a million tiny __________ where the process of urine formation takes place.
Nephrons
c. Aquatic animals excrete solid waste in gaseous form called __________, while land animals excrete a white semi-colored compound called __________ because of less intake of water.
– Ammonia (aquatic animals)
– Uric acid (land animals)
– Uric acid (land animals)
d. Systole: __________ (Fill in the blank)
Systole refers to the phase of the heartbeat when the heart contracts to pump blood.
e. Veins have __________ to prevent the backflow of blood.
Valves
Q2. Answer the following questions:
a. What is the function of platelets in the blood, and why is their normal count essential for the body?
– Function: Platelets help in blood clotting, preventing excessive bleeding during injuries.
– Importance: A low platelet count can lead to excessive bleeding, while a high platelet count may cause blood clots, leading to complications.
– Importance: A low platelet count can lead to excessive bleeding, while a high platelet count may cause blood clots, leading to complications.
b. A farmer is growing vegetables in a field where the soil has become dry due to a lack of rainfall. The farmer waters the plants, and after some time, notices that the leaves appear fresh and upright again.
i. What process allows water to move into the plant’s roots from the soil?
Osmosis (movement of water from a region of higher concentration in the soil to lower concentration in the root cells).
ii. If a concentrated salt solution is poured near the plant roots instead of water, what might happen to the plant cells? Explain your answer using the concept of osmosis.
– The high salt concentration outside the roots will cause water to move out of the plant cells (due to osmosis).
– This will lead to plasmolysis, where plant cells shrink, making the plant wilt and eventually die.
– This will lead to plasmolysis, where plant cells shrink, making the plant wilt and eventually die.
iii. Differentiate between the movement of water (osmosis) and the movement of oxygen gas into the cells during respiration (diffusion).
| Osmosis | Diffusion |
|---|---|
| Movement of water molecules through a semi-permeable membrane. | Movement of gases or solutes from high to low concentration. |
| Requires a semi-permeable membrane. | Does not require a membrane. |
| Example: Water absorption by plant roots. | Example: Oxygen entering cells for respiration. |
c. Why are arteries more prone to damage from high blood pressure compared to veins? Why are veins less affected?
– Arteries carry blood under high pressure, which puts more strain on their walls, making them more susceptible to damage.
– Veins carry blood under low pressure and have valves that help prevent backflow, reducing the risk of damage.
– Veins carry blood under low pressure and have valves that help prevent backflow, reducing the risk of damage.