Excretion: Biology Class-note

Excretion is the process by which waste products and excess materials are removed from an organism’s body. These waste products can be in the form of toxic substances, excess ions, and metabolic by-products, and their removal is necessary to maintain homeostasis and prevent damage to the organism. In this class note, we will discuss the different types of excretory structures and excretory mechanisms found in various organisms.

Types of Excretory Structures:

Contractile Vacuole: Found in single-celled organisms, the contractile vacuole is a spherical structure that helps regulate the water balance of the cell. It collects excess water and then contracts, expelling the water out of the cell.

Flame Cell: Found in flatworms, the flame cell is a type of excretory structure that helps remove metabolic waste products from the body. The waste is carried away in a network of tubes and then expelled from the organism.

Nephridium: Found in annelids (such as earthworms), the nephridium is a tubular structure that performs the function of excretion. Nephridia remove metabolic waste products from the body and regulate the balance of ions in the organism.

Malpighian Tubules: Found in insects, the Malpighian tubules are structures that help remove metabolic waste products from the body. They are similar to the nephridia in annelids, and they help regulate the water and ion balance in the organism.

Kidney: Found in vertebrates, the kidney is a complex excretory organ that performs a range of functions, including removing metabolic waste products, regulating water balance, and controlling blood pressure.

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Stoma: Found in plants, stomata are small pores on the surface of leaves that help regulate water balance and exchange gases between the plant and the environment.

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Science Facts

Lenticel: Found in plants, lenticels are small pores on the surface of stems and roots that help exchange gases between the plant and the environment.

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Excretory Mechanisms:

Kidneys: Kidneys are the primary excretory organs in vertebrates and play a crucial role in removing metabolic waste products from the body and regulating water balance.

Lungs: In humans and other vertebrates, the lungs play a role in the excretion of carbon dioxide, a waste product produced during cellular respiration.

Skin: The skin is also involved in excretion, as it helps regulate the body’s water balance and removes waste products in the form of sweat.

what are Excretory products of plants

Plants, like all living organisms, produce waste products as a result of their metabolic processes. Some of the main excretory products in plants are:

Carbon Dioxide: It is produced during photosynthesis and respiration and is released into the air through small openings in the leaves called stomata.

Oxygen: During photosynthesis, plants produce oxygen and release it into the air.

Water: Plants release water as a result of transpiration, which is the process of water movement through the plant and evaporation from the leaves.

Sugars: During photosynthesis, plants produce excess sugars that they do not need for immediate energy. These excess sugars can be stored in the plant or excreted as waste.

Organic Acids: As plants metabolize food, they produce organic acids such as citric acid, which can be excreted as waste.

Hormones: Hormones play a role in regulating growth and development in plants, and excess hormones can be excreted as waste.

Overall, the excretory products of plants play a critical role in the functioning and survival of both the plant and the surrounding ecosystem.

Tannins: These are a type of polyphenolic compound that are produced and stored in various parts of the plant, including the leaves, stems, and fruits. They have many functions, including acting as a defense mechanism against herbivores and pathogens.

Resins: Resins are produced by some trees and are stored in specialized glands. They serve as a defense mechanism against herbivores and insects, and they also have antimicrobial properties.

Gums: Gums are sticky, water-soluble substances produced by plants. They serve a variety of functions, including acting as a sealant to prevent water loss, providing support to plant tissues, and helping to store energy.

Mucilage: Mucilage is a thick, gooey substance produced by some plants. It helps to retain water and provides a supportive structure for the plant.

Alkaloids: Alkaloids are a class of nitrogen-containing compounds that are produced by a number of plant species. They serve as a defense mechanism against herbivores and have medicinal properties.

In conclusion, excretion is a vital process that helps maintain homeostasis and prevent damage to the organism. Different organisms have different excretory structures and mechanisms to remove waste products, but the ultimate goal is the same: to maintain a healthy balance within the organism.

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