Excretion In Animals & Plants - 1 - SSS 1 MCQ

Unicellular organisms remove metabolic wastes by allowing them to diffuse from their body surface into the surrounding water.

• The main purpose of the excretory system in human beings is to remove waste products and excess substances from the body.
• This system includes organs such as the kidneys, ureters, bladder, and urethra, which work together to filter blood, remove waste products (such as urea, creatinine, and excess salts), regulate water balance, and maintain the body's acid-base balance.

The excretory system in humans includes kidneys, ureters, bladder, and urethra.

• The kidneys are located in the abdominal cavity, one on either side of the backbone.
• The kidneys are located in the abdomen, specifically in the upper abdominal cavity, on either side of the spine.
• They are positioned against the back muscles and typically extend from the T12 to L3 vertebrae.
• The right kidney is slightly lower than the left kidney due to the position of the liver.

• The nephron is the basic filtration unit in the kidneys.
• Each kidney contains millions of nephrons, which are responsible for filtering blood and producing urine.
• The nephron consists of several parts, including the glomerulus, Bowman's capsule, renal tubules, and collecting ducts.

Bowman's capsule collects the filtrate from the glomerulus in the kidneys.

• During the process of urine formation in the kidneys, the initial filtrate from the blood (which includes water, ions, glucose, amino acids, urea, and other substances) passes through the renal tubules.
• As this filtrate moves along the tubules, various substances are selectively reabsorbed back into the bloodstream to maintain the body's balance of water and solutes.

• Urine is stored in the urinary bladder before it is expelled from the body through the urethra.
• The bladder is a muscular sac located in the pelvis that expands as it fills with urine from the kidneys via the ureters.

• The urge to pass urine (urination or micturition) is triggered by the expansion of the urinary bladder.
• As urine accumulates in the bladder, stretch receptors in the bladder wall send signals to the brain, indicating that the bladder is full and needs to be emptied.
• This sensation of bladder fullness leads to the conscious urge to urinate.

Plants do not actively transport waste into the atmosphere; they primarily use methods such as transpiration, storage in vacuoles, and shedding of leaves for excretion.

• The glomerulus is a network of capillaries within the nephron that performs the initial filtration of blood. It is surrounded by Bowman’s capsule, which collects the filtered urine. The glomerulus plays a crucial role in filtering waste products from the blood.

• Bowman's capsule, also known as the glomerular capsule, is the structure in the kidney responsible for the initial filtration of blood. It is part of the nephron, which is the functional unit of the kidney.
• The glomerulus, a network of capillaries, is located within Bowman's capsule.
• Blood flows into the glomerulus under high pressure, and small molecules such as water, ions, glucose, amino acids, and waste products are filtered from the blood into the Bowman's capsule to form the glomerular filtrate.

The kidneys filter waste products such as urea and uric acid from the blood, which is the primary function of these organs in the excretory system.

Urea is a waste product and is not reabsorbed; instead, it is excreted in the urine. Glucose, amino acids, and salts are selectively reabsorbed.

• Plants primarily get rid of excess water through transpiration.
• Transpiration is the process by which water evaporates from the surfaces of plant leaves, mainly through small openings called stomata.
• This loss of water vapor helps plants regulate their internal water balance, cool down, and transport nutrients from the roots to the leaves.
• Transpiration plays a crucial role in maintaining the plant's health and facilitating the movement of water and minerals throughout the plant.

The urinary bladder stores urine until the pressure from the expanded bladder creates the urge to urinate, at which point it is expelled through the urethra.

• Selective reabsorption of substances such as glucose, amino acids, salts, and water occurs in the tubules of the nephron.
• After the initial filtration of blood in Bowman's capsule (glomerular filtration), the resulting fluid (glomerular filtrate) enters the renal tubules.
• The proximal convoluted tubule (PCT) is primarily responsible for reabsorbing most of the filtered substances back into the bloodstream.
• This selective reabsorption process ensures that essential substances are retained in the body while excess waste products and ions are excreted in urine.

Plants do not excrete urea and uric acid. These are nitrogenous wastes primarily excreted by animals. Plants handle waste products through vacuoles, fallen leaves, and excretion into the soil.

• The muscular urinary bladder plays a crucial role in the excretory system by storing urine temporarily until it can be excreted from the body through the urethra.
• The bladder expands as it fills with urine, and its muscular walls contract to expel urine during urination (micturition).

Having nephrons packed close together maximizes the kidney's ability to filter blood efficiently by providing a large surface area for filtration.

The excretory system in humans includes kidneys, ureters, bladder, and urethra.

The kidneys are located in the abdominal cavity, one on either side of the backbone.

• The nephron is the basic filtration unit in the kidneys.
• Each kidney contains millions of nephrons, which are responsible for filtering blood and producing urine.
• The nephron consists of several parts, including the glomerulus, Bowman's capsule, renal tubules, and collecting ducts.
• The glomerulus and Bowman's capsule together form the initial filtration unit where blood plasma is filtered into the nephron.

Bowman's capsule collects the filtrate from the glomerulus in the kidneys.

• During photosynthesis in plants, carbon dioxide (CO2) is taken in from the atmosphere, and water (H2O) is absorbed from the soil.
• In the presence of sunlight and chlorophyll, these raw materials are converted into glucose (C6H12O6) and oxygen (O2).
• Oxygen is a waste product of photosynthesis and is released into the atmosphere through stomata in plant leaves.