Class 7 Science Chapter 11 Notes: Transportation In Animals And Plants

This chapter is crucial for understanding how essential substances like nutrients, water, oxygen, and waste products move within living organisms. For CBSE Class 7 Science students, mastering 'Transportation In Animals And Plants' is key to scoring well in exams, as it often features questions on diagrams of the heart, blood circulation, and the functions of xylem and phloem. These notes offer a concise, exam-focused summary, breaking down complex concepts into easy-to-understand points. YoLearn.ai's revision tools, such as Flashcards for definitions, Quizzes for self-assessment, and Mind Maps for visualizing complex processes, can significantly enhance your preparation. Use these notes as your foundation and our AI tools to solidify your understanding and ensure you're fully prepared for any question that comes your way.

Must Remember: Key Concepts

Circulatory System in animals transports blood containing digested food, oxygen, water, and waste products.
Blood consists of plasma, red blood cells (RBCs), white blood cells (WBCs), and platelets.
The heart is a muscular organ that pumps blood throughout the body.
Blood vessels (arteries, veins, capillaries) form a network for blood flow.
Arteries carry oxygen-rich blood away from the heart; veins carry carbon dioxide-rich blood towards the heart.
Capillaries are thin-walled vessels connecting arteries and veins, facilitating exchange.
Excretion is the removal of waste products from the body; the kidneys are key excretory organs.
In plants, xylem transports water and minerals from roots to leaves.
Phloem transports food (synthesized in leaves) to all parts of the plant.
Transpiration is the loss of water from leaves in the form of water vapour.

Key Terminology

Blood: A fluid connective tissue that circulates throughout the body, transporting essential substances and waste products.
Plasma: The liquid component of blood, consisting mostly of water, in which blood cells are suspended.
Hemoglobin: A red pigment in red blood cells that binds with oxygen and transports it to all parts of the body.
Heartbeat: The rhythmic contraction and relaxation of the heart muscles that pump blood.
Pulse: The throbbing sensation felt in arteries due to blood being pushed through them by the heart.
Transpiration: The process by which plants lose water in the form of water vapour from the aerial parts, mainly through stomata in leaves.
Xylem: Plant tissue responsible for transporting water and dissolved minerals from the roots up to the rest of the plant.
Phloem: Plant tissue responsible for transporting food (sugars) synthesized during photosynthesis from the leaves to other parts of the plant.
Dialysis: An artificial process of removing waste products and excess fluid from the blood when kidneys fail.

The Human Circulatory System: A Lifeline

The circulatory system is a vital transport network in animals, responsible for carrying substances throughout the body. It consists of the heart, blood, and blood vessels.

Blood is a fluid connective tissue with several components:

Plasma: The liquid part of blood, carrying nutrients, hormones, and waste products.
Red Blood Cells (RBCs): Contain hemoglobin, a red pigment that binds with oxygen and transports it to all body cells. A deficiency of hemoglobin leads to anaemia.
White Blood Cells (WBCs): Fight against germs that enter the body, acting as the body's defense mechanism.
Platelets: Help in blood clotting at the site of injury, preventing excessive blood loss.

The heart is a muscular organ located in the chest cavity, slightly tilted to the left. It works continuously, pumping blood without rest. The human heart has four chambers: two upper chambers called atria (singular: atrium) and two lower chambers called ventricles. The walls separating these chambers prevent the mixing of oxygen-rich blood and carbon dioxide-rich blood.

Blood vessels are tubes through which blood flows. There are three main types:

Arteries: Carry oxygen-rich blood from the heart to all parts of the body. They have thick, elastic walls because blood flows under high pressure.
Veins: Carry carbon dioxide-rich blood from all parts of the body back to the heart. They have thinner walls and contain valves to prevent the backflow of blood.
Capillaries: Extremely thin and narrow blood vessels that connect arteries to veins. They facilitate the exchange of gases, nutrients, and waste products between blood and body cells. Oxygen and digested food pass into the cells, while carbon dioxide and waste products from cells enter the blood.

Journey of Blood: The Circulation Pathway

Transportation in Plants: Water, Minerals, and Food

Unlike animals, plants do not have a circulatory system with a heart and blood. Instead, they have specialized tissues for transporting water, minerals, and food throughout their body. This transport is crucial for their survival and growth.

Water and Mineral Transport: Plants absorb water and minerals from the soil through their roots. The root hairs increase the surface area for absorption. The absorbed water and minerals are then transported upwards to the leaves and other aerial parts through a specialized tissue called xylem.

Xylem: Forms a continuous network of channels that connects the roots to the stem, branches, and leaves, thus transporting water and dissolved minerals throughout the plant. The upward movement of water is largely driven by transpiration pull.

Food Transport: Leaves are the 'food factories' of the plant, where food (sugars) is synthesized during photosynthesis. This food needs to be transported to all other parts of the plant, including roots, fruits, and growing regions, for energy and storage. This transport is carried out by another specialized tissue called phloem.

Phloem: Transports the prepared food from the leaves to all other parts of the plant. Unlike xylem, phloem transport can be bidirectional (upwards or downwards) depending on the plant's needs.

Transpiration: This process is the evaporation of water from the leaves and other aerial parts of a plant in the form of water vapour. Most of this water loss occurs through tiny pores called stomata on the surface of leaves. Transpiration creates a 'suction pull' (transpirational pull) which helps in drawing water and minerals up from the roots to great heights in tall trees. It also helps in cooling the plant.

Xylem vs. Phloem: The Plant's Transport Duo

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Exam Success Tips for Transportation

To excel in this chapter, focus on diagrams. Practice drawing and labeling the human heart and the key parts of the circulatory system. Also, understand the pathway of water and food in plants, visualizing xylem and phloem. Definitions are crucial; be precise with terms like 'hemoglobin', 'transpiration', 'arteries', and 'veins'. Questions often test the functions of different blood components and plant tissues. Remember the direction of blood flow in arteries and veins, and the role of valves in the heart and veins. For plants, clearly distinguish between the functions of xylem and phloem. Pay attention to how environmental factors affect transpiration.

Practice Questions with Solutions

Q: What is the main function of hemoglobin in blood? A: Hemoglobin binds with oxygen and transports it to all parts of the body.
Q: Name the two types of blood vessels that carry blood to and from the heart. A: Arteries carry blood away from the heart, and veins carry blood towards the heart.
Q: Which plant tissue is responsible for transporting water and minerals from the roots to the leaves? A: Xylem is responsible for transporting water and minerals.
Q: What is transpiration and why is it important for plants? A: Transpiration is the loss of water vapour from plant leaves. It creates a suction pull that helps in the absorption and upward movement of water and minerals, and also helps cool the plant.

Frequently Asked Questions

What is the difference between arteries and veins?

Arteries carry oxygenated blood away from the heart to the body, have thick, elastic walls due to high pressure, and do not have valves (except pulmonary artery). Veins carry deoxygenated blood back to the heart, have thinner walls, and contain valves to prevent backflow of blood.

How does the heart prevent the mixing of oxygenated and deoxygenated blood?

The human heart is divided into four distinct chambers by muscular walls called septa. This structural separation ensures that oxygen-rich blood from the left side does not mix with carbon dioxide-rich blood from the right side, maintaining efficient oxygen delivery.

Why is transportation necessary in plants?

Transportation is essential in plants to move water and minerals absorbed from roots to leaves for photosynthesis, and to distribute the food produced in leaves to all other parts for growth, energy, and storage. Without efficient transport, plants cannot survive.

What happens if a person's kidneys fail?

If a person's kidneys fail, waste products like urea accumulate in the blood, which can be life-threatening. In such cases, the blood is filtered artificially through a process called dialysis, using a kidney machine to remove harmful waste products.