All questions of Transportation in Animals and Plants for Class 7 Exam

Plants lose gallons of water every day through the process of transpiration, the evaporation of water from plants primarily through pores in their leaves. Up to 99% of the water absorbed by roots is lost via transpiration through plant leaves.

Urea is the primary waste product of protein metabolism in humans, excreted by the kidneys in urine.

Role of White Blood Cells (WBCs)
White blood cells (WBCs), or leukocytes, are a crucial component of the immune system. Their primary role is to protect the body against infections and diseases.
Key Functions of WBCs
- Defense Against Pathogens:
WBCs identify and eliminate pathogens such as bacteria, viruses, fungi, and parasites. They recognize these foreign invaders and initiate an immune response.
- Types of WBCs:
There are several types of WBCs, each with specific functions:
- Neutrophils: The most abundant WBCs that act quickly to engulf and destroy pathogens.
- Lymphocytes: Include B cells and T cells, which play critical roles in adaptive immunity, recognizing and remembering specific pathogens.
- Monocytes: These cells transform into macrophages and help clear out dead cells and debris, as well as engulf pathogens.
- Eosinophils and Basophils: Involved in allergic reactions and combating parasites.
Immune Response Activation
- Response Coordination:
WBCs communicate with each other and with other immune system components to coordinate the body’s response to infections.
- Inflammation:
Upon detecting an infection, WBCs release chemicals that trigger inflammation, increasing blood flow to the affected area, bringing more immune cells to fight the infection.
Conclusion
In summary, the correct answer is option 'B' because white blood cells are vital for fighting against germs and protecting the body from various diseases. Their ability to detect, respond, and eliminate pathogens makes them essential for maintaining health and preventing infections.

Fishes and other aquatic animals remove waste chemicals from their bodies by excreting cell waste as ammonia, which can easily dissolve in water. This helps them to get rid of harmful substances and maintain a healthy internal environment.

Water and Nutrient Transport in Plants
Plants rely on specialized structures to transport water and nutrients effectively. The correct answer is option 'B': through their stems using xylem vessels.
Understanding Xylem Vessels
- Xylem is a type of vascular tissue in plants.
- It is responsible for the upward transport of water and dissolved minerals from the roots to the rest of the plant.
- The structure of xylem vessels is designed to facilitate efficient water movement.
How Water Moves Through Xylem
- Water absorption occurs in the roots, where tiny root hairs increase surface area.
- Once absorbed, water travels through xylem vessels via capillary action and transpiration pull.
- Transpiration, the process of water evaporation from leaves, creates a negative pressure that helps draw water upward.
Nutrient Transport
- Along with water, essential nutrients dissolved in it are transported through xylem.
- Nutrients such as nitrogen, phosphorus, and potassium are vital for plant growth and development.
Comparison with Other Options
- Option 'A' (Through their leaves) is incorrect as leaves primarily perform photosynthesis, not transport.
- Option 'C' (Through their flowers) is also incorrect; flowers are mainly for reproduction.
- Option 'D' (Through their roots using phloem tissue) is misleading because phloem is responsible for transporting sugars and organic nutrients, not primarily water.
Conclusion
In summary, xylem vessels play a crucial role in transporting water and nutrients throughout the plant. This efficient system ensures that all parts of the plant receive the necessary resources for growth and survival.

Immediate Consequence of No Platelets in the Blood:
Platelets play a crucial role in blood clotting, so if there were no platelets in the blood, the immediate consequence would be:

Uncontrollable Bleeding:
Without platelets, the blood would not be able to clot properly. Platelets are responsible for forming clots at the site of a wound, which helps to stop bleeding. In the absence of platelets, even a small cut or injury could lead to excessive bleeding that would be difficult to control. This could potentially be life-threatening, especially in cases of major injuries or surgeries.
In addition to their role in blood clotting, platelets also play a role in wound healing and tissue repair. Without platelets, the body's ability to repair damaged tissues would be compromised, further exacerbating the consequences of uncontrollable bleeding.
In conclusion, the immediate consequence of having no platelets in the blood would be uncontrollable bleeding, which could lead to severe health complications and even death.

Importance of Oxygen Transport in Animals
Animals, like all living organisms, require oxygen for cellular respiration, a process that converts food into energy. This energy is essential for various physiological functions, including movement, growth, and reproduction.
Role of Blood in Oxygen Transport
- Blood is the main transport medium in animals.
- It carries oxygen from the lungs or gills to all body cells.
- Hemoglobin, a protein in red blood cells, binds to oxygen, facilitating its transport.
Removal of Wastes
Animals also produce metabolic waste, such as carbon dioxide (CO2) and urea, which are harmful if accumulated in the body.
- Blood helps in transporting CO2 from body cells back to the lungs for exhalation.
- It also carries urea from the liver to the kidneys for excretion.
Circulatory System's Role
The circulatory system plays a crucial role in:
- Ensuring a continuous supply of oxygen to tissues.
- Removing waste products efficiently.
- Maintaining homeostasis, which is vital for overall health.
Conclusion
In summary, the statement is true: Animals need to transport oxygen and wastes in their body through the circulatory system, ensuring that they can function properly and thrive in their environments.

Excretory System in Humans
The excretory system in humans is responsible for removing waste products from the body. It plays a crucial role in maintaining the body's internal environment by filtering and eliminating metabolic waste products.

Components of the Excretory System
- Kidneys: The kidneys are bean-shaped organs that filter waste products from the blood to form urine. They also help regulate blood pressure and electrolyte balance.
- Ureters: The ureters are tubes that carry urine from the kidneys to the bladder. They ensure the flow of urine from the kidneys to the bladder.
- Bladder: The bladder is a muscular organ that stores urine until it is ready to be excreted from the body. It expands as it fills up with urine.
- Urethra: The urethra is a tube that carries urine from the bladder to the outside of the body during urination. It also plays a role in the excretory process.

Function of the Excretory System
The excretory system performs the vital function of removing waste products such as urea, excess salts, and water from the body. It helps maintain the body's internal balance and prevents the accumulation of harmful substances.
Therefore, the statement that the excretory system in humans includes the kidneys, ureters, bladder, and urethra is True. These organs work together to eliminate waste products and maintain the body's overall health and function.

Understanding Water Absorption in Plants
In plants, the structure primarily responsible for the absorption of water is the root hairs.
What Are Root Hairs?
- Root hairs are tiny, hair-like extensions that grow from the root's surface.
- They significantly increase the surface area of the roots, allowing for more efficient water and nutrient absorption.
How Do Root Hairs Function?
- Root hairs penetrate the soil and come into contact with water molecules.
- They absorb water through a process called osmosis, where water moves from an area of higher concentration (the soil) to an area of lower concentration (inside the root hairs).
- This process is crucial for the plant’s hydration and nutrient uptake.
Other Structures in Water Movement
- Xylem: While root hairs absorb water, the xylem is responsible for transporting this water throughout the plant.
- Stomata: These are small openings on leaves for gas exchange and play a role in water loss, not absorption.
- Phloem: This structure is involved in the transport of nutrients and sugars, not water.
Importance of Root Hairs
- Root hairs are essential for plant health as they ensure that the plant receives adequate water, especially during dry conditions.
- They also aid in the uptake of minerals, contributing to the overall nutrition and growth of the plant.
In summary, root hairs are the key structures that absorb water in plants, making them vital for hydration and nutrient intake.