1. Ammonia
- Definition- Ammonia is a nitrogenous waste product formed during the metabolic activities in organisms.
- Explanation- Inside the body of organisms, various metabolic activities occur, resulting in the production of waste substances. Ammonia is one such waste product, originating primarily from the breakdown of proteins and nucleic acids. Being highly toxic, it needs to be swiftly and efficiently eliminated from the body to maintain the organism’s health and prevent harm to cellular structures.
2. Artery
- Definition- Arteries are muscular blood vessels that carry blood away from the heart to various parts of the body.
- Explanation- Arteries form a significant component of the circulatory system, responsible for transporting oxygen-rich blood from the heart to various tissues and organs, supporting their functional and metabolic requirements. With muscular and elastic walls, arteries are adapted to handle and maintain the pressure of the pulsating flow of blood propelled by the heart’s contractions.
Also Check – Differences between Arteries and Veins for Class 7
3. Blood
- Definition- Blood is a vital body fluid responsible for transporting essential nutrients, oxygen, and waste products throughout the body.
- Explanation- Blood, consisting of plasma, red blood cells, white blood cells, and platelets, acts as the body’s internal transportation system. It circulates continuously, delivering oxygen and necessary nutrients to cells, aiding in various cellular activities and metabolic processes, and also playing a crucial role in the removal and disposal of waste products.
4. Blood Vessels
- Definition- Blood vessels are tubular structures that serve as pathways for the transportation of blood throughout the body.
- Explanation– Blood vessels, encompassing arteries, veins, and capillaries, form an extensive network that facilitates the continuous flow of blood. They ensure that each body part, from organs to cells, receives the essential substances required for proper functionality and metabolic activities.
5. Capillary
- Definition- Capillaries are the smallest, thinnest blood vessels where the exchange of nutrients, oxygen, and waste products occurs between the blood and body cells.
- Explanation- Capillaries act as a bridge between arteries and veins, enabling the crucial exchange of substances. Their walls are thin, allowing oxygen and nutrients to pass through to the cells, and waste products to be collected into the bloodstream, promoting cellular health and function.
6. Circulatory System
- Definition- The circulatory system is an intricate network composed of the heart, blood vessels, and blood, dedicated to transporting substances throughout the body.
- Explanation- The circulatory system operates as the body’s transportation highway, ensuring that essential nutrients, oxygen, and other necessary substances reach their respective destinations, supporting the overall functionality and well-being of the organism. It also assists in the removal of waste products, contributing to the body’s homeostasis and internal balance.
7. Dialysis
- Definition- Dialysis is a medical procedure that performs the functions of kidneys artificially when they are not working properly, helping remove waste products and excess fluids from the blood.
- Explanation- Since kidneys play a crucial role in filtering waste from the blood, when they fail, harmful wastes can accumulate. Dialysis acts as an artificial kidney, cleaning the blood by removing unwanted waste products and excess fluids, ensuring the body’s internal environment remains balanced and conducive for all other organ functions.
8. Excretion
- Definition- Excretion is the biological process where waste products produced during metabolic activities are eliminated from an organism’s body.
- Explanation- Excretion is vital for maintaining the body’s internal balance or homeostasis. By getting rid of waste products generated during metabolic processes, like ammonia and urea, it ensures that the body’s internal environment remains conducive for the proper functioning of cells and organs.
9. Excretory System
- Definition- The excretory system is a collection of organs and vessels responsible for removing waste products and excess substances from the body.
- Explanation- The excretory system, including the kidneys, ureters, bladder, and urethra, collaboratively works towards the elimination of metabolic wastes. This system helps maintain the body’s water balance and overall homeostasis, ensuring that body functions proceed seamlessly without the interference of toxic substances.
10. Haemoglobin
- Definition- Haemoglobin is a red protein in red blood cells responsible for transporting oxygen from the lungs to body tissues and helping return carbon dioxide from tissues to the lungs.
- Explanation– Haemoglobin plays a crucial role in respiratory processes, carrying oxygen molecules inhaled during breathing from the lungs to various body tissues and organs, ensuring that metabolic activities proceed efficiently. It also assists in transporting carbon dioxide, a waste product of metabolism, back to the lungs for elimination.
11. Heart Beat
- Definition- A heartbeat is a single cycle in which the heart contracts and relaxes to pump blood, consisting of systole (contraction) and diastole (relaxation).
- Explanation- Every heartbeat ensures that blood, carrying essential nutrients and oxygen, is efficiently pumped and circulated throughout the body. This rhythmic beating, maintained and regulated through electrical signals, is fundamental for sustaining life and supporting the functionality of various organs and systems.
12. Kidneys
- Definition- Kidneys are bean-shaped organs that filter waste products, excess substances, and extra water from the blood, converting them into urine for elimination.
- Explanation- Kidneys are essential organs in the excretory system, continuously working to maintain the body’s internal balance. By filtering blood, they help manage waste elimination, maintain appropriate water levels, and ensure that useful substances, like certain salts and minerals, are reabsorbed and reused by the body.
13. Phloem
- Definition- Phloem is a type of vascular tissue in plants responsible for transporting nutrients, including the sugars produced during photosynthesis, from leaves to other parts of the plant.
- Explanation- Phloem plays an essential role in the plant’s nutrient transportation system. It carries the food produced from photosynthesis in the leaves to various parts of the plant, ensuring that every part receives the necessary nutrients for growth and energy. This transport system allows for the distribution of essential organic compounds to all areas of the plant, facilitating various biological functions.
14. Plasma
- Definition- Plasma is the liquid component of blood, making up about 55% of its total volume. It carries cells and platelets throughout the body and helps in transporting nutrients, hormones, and waste products.
- Explanation- Plasma acts as a carrying medium within blood, transporting red and white blood cells and platelets throughout the body. It also carries waste products for excretion and essential nutrients and hormones, ensuring the proper functioning of body cells and organs, and maintaining overall body homeostasis.
15. Platelets
- Definition- Platelets, or thrombocytes, are small cell fragments in the blood that play a crucial role in clotting and preventing excessive bleeding when injuries occur.
- Explanation- Platelets are essential for the blood clotting process. When an injury occurs, they migrate to the site, clump together, and work with other clotting factors to form a plug that prevents excessive bleeding, allowing the healing process to commence.
16. Pulse
- Definition- Pulse refers to the rhythmic beating or throbbing, usually felt at various pulse points in the body, caused by the pumping action of the heart circulating blood through the arteries.
- Explanation- The pulse rate is an indicator of the heart’s activity level, representing the number of heartbeats per minute. It can be felt at different parts of the body, like the wrist or neck, where arteries are close to the skin, reflecting the heart’s efficiency in pumping blood and supplying the body with necessary oxygen and nutrients.
17. Red Blood Cell
- Definition- Red blood cells (RBCs), or erythrocytes, are cells in the blood that contain haemoglobin and are responsible for transporting oxygen from the lungs to body tissues and removing carbon dioxide.
- Explanation- Red blood cells are essential carriers of oxygen, allowing for the efficient transportation of inhaled oxygen from the lungs to various cells and tissues in the body. They also assist in carrying carbon dioxide, a waste product of cellular metabolism, back to the lungs for exhalation, facilitating the maintenance of a healthy internal environment.
18. Root Hair
- Definition- Root hairs are tiny, hair-like structures found on plant roots that increase the surface area for absorption, helping in the intake of water and nutrients from the soil.
- Explanation- Root hairs enhance a plant’s ability to absorb water and essential minerals from the soil. By increasing the root’s surface area, they optimise the absorption process, ensuring that the plant receives the necessary water and nutrients required for growth and various metabolic activities.
19. Stethoscope
- Definition- A stethoscope is a medical instrument used primarily for listening to internal sounds of a human body, such as heartbeats and breathing sounds.
- Explanation- The stethoscope allows for the amplification of internal body sounds, facilitating the examination and diagnosis of a patient’s health, particularly related to the heart and lungs. It is instrumental in detecting abnormalities or irregularities in heartbeats and breathing patterns, assisting in preliminary diagnosis and continuous monitoring.
20. Sweat
- Definition- Sweat is a clear, salty liquid produced by glands in the skin of mammals that helps maintain body temperature by facilitating cooling through evaporation.
- Explanation- Sweating is an essential mechanism for body temperature regulation, where it helps in cooling the body during high temperatures or physical exertion. It also aids in the removal of certain waste products from the body, contributing to the maintenance of homeostasis.
21. Tissue
- Definition- Tissue refers to a group of cells that function together to perform a specific activity in an organism.
- Explanation- Tissues comprise cells and extracellular materials that collaboratively execute specialised functions. In plants, for example, vascular tissues like xylem and phloem facilitate the transport of water, nutrients, and food throughout the plant, contributing to its overall growth and development.
22. Urea
- Definition- Urea is a nitrogenous waste product resulting from the metabolism of proteins, expelled from the body mainly through urine.
- Explanation- Urea is produced in the liver and transported to the kidneys, where it is expelled from the body. It plays a crucial role in the excretory system, helping to rid the body of nitrogenous wastes, thus maintaining a balanced internal environment.
23. Ureter
- Definition- The ureter is a muscular tube that transports urine from the kidneys to the urinary bladder for temporary storage.
- Explanation– Ureters play a vital role in the human excretory system. They facilitate the movement of urine from the kidneys, where it is produced, ensuring its smooth passage towards the urinary bladder, where it is stored until expulsion.
24. Urethra
- Definition- The urethra is a duct that conveys urine from the urinary bladder to the outside of the body for elimination.
- Explanation- The urethra acts as a conduit for urine expulsion, finalising the excretion process. In males, it also functions in the reproductive system, allowing for the passage of semen.
25. Uric Acid
- Definition- Uric acid is a waste product formed from the metabolic breakdown of purine nucleotides.
- Explanation- Uric acid is primarily excreted through urine. It is relatively insoluble and tends to form crystals, which, in excess, can lead to conditions like gout or kidney stones. Different animals have varying levels of uric acid in their excretory systems based on their metabolic needs and survival adaptations.
26. Urinary Bladder
- Definition- The urinary bladder is a muscular sac in the pelvis, primarily involved in storing urine, allowing urination to be infrequent and voluntary.
- Explanation- The urinary bladder collects urine excreted by the kidneys before disposal by urination. It plays a critical role in the human excretory system, ensuring that urine is expelled from the body in a controlled and regulated manner, maintaining internal homeostasis.
27. Vein
- Definition- Veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart.
- Explanation- Veins form an essential component of the circulatory system, ensuring that blood is returned to the heart to be pumped once more to the lungs for oxygenation. They operate in tandem with other vessels, like arteries and capillaries, to sustain the body’s circulatory function, vital for the transportation of essential nutrients, oxygen, and waste products.
28. White Blood Cell
- Definition- White blood cells (WBCs), also known as leukocytes, are cells of the immune system involved in protecting the body against both infectious disease and foreign invaders.
- Explanation- White blood cells play a crucial role in the immune system. They are involved in combating infections, responding to foreign invaders, and aiding in the recovery process during illness. Different types of WBCs have various roles, such as recognizing pathogens, destroying harmful bacteria, and creating antibodies.
29. Xylem
- Definition- Xylem is a type of vascular tissue in plants that primarily functions in transporting water and dissolved minerals upwards from the roots to the rest of the plant.
- Explanation- Xylem’s role in plants is vital for their survival and growth. It not only aids in transporting water and essential minerals but also offers structural support to plants. The flow within the xylem is unidirectional, meaning it moves from the roots, supplying necessary nutrients across different parts of the plant to facilitate various metabolic processes.
Also Check – NCERT Solutions for Class 7 Science Chapter 11-Transportation in Animals and Plants
Class 7 Science- Chapter 11- Transportation in Animals and Plants – Complete Notes
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Class 7 – Science- Chapter 11-Transportation in Animals and Plants Question Answer (Solved MCQs)
