Excretion Flashcards
How do plants release oxygen and carbon dioxide?
Plants release oxygen and carbon dioxide through the stomata of leaves as waste products of metabolism.
What factors affect the waste products in plants?
The intensity of light affects the waste products, including oxygen, carbon dioxide, water vapor, and other unwanted substances within plants.
What happens during the day in plants when there is sufficient light?
- During the day, when there is sufficient light, the rate of photosynthesis is higher than the rate of respiration in plants.
- More oxygen is released than used in respiration, and less carbon dioxide is released than used in photosynthesis, resulting in oxygen being in excess as a waste product.
What happens at night in plants when there is insufficient light?
- At night, when there is insufficient light, there is no photosynthesis, only respiration.
- This leads to oxygen being used in respiration and carbon dioxide being produced.
- Since no photosynthesis occurs, no carbon dioxide is used, resulting in carbon dioxide being in excess as a waste product.
What are the excretory products of the kidneys, lungs, and skin in humans?
- The kidneys excrete urea, water, and mineral ions as urine.
- The lungs remove carbon dioxide and water when we breathe out. (exhalation)
- The skin removes water and salt by sweating.
What is the function of the kidneys in excretion and osmoregulation?
The kidneys regulate the water content of the blood to maintain blood pressure and excrete toxic waste products of metabolism and substances in excess.
How does osmoregulation occur in the kidney?
Osmoregulation occurs in the kidney through the release of anti-diuretic hormone (ADH) from the pituitary gland, which makes the walls of the collecting duct more permeable to water, allowing more water to be reabsorbed into the blood, making the urine more concentrated.
Describe the structure of the urinary system.
- The urinary system consists of the kidneys, ureters, bladder, and urethra.
- The kidneys filter the blood, and the urine is then passed through the ureters to the bladder, where it is stored until it is released through the urethra.
What is the structure of a nephron?
A nephron consists of the Bowman’s capsule, glomerulus, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct.
How does ultrafiltration occur in the Bowman’s capsule?
Ultrafiltration occurs in the Bowman’s capsule when blood flows from the renal artery into the glomerulus under high pressure, causing small molecules such as water, urea, salts, and glucose to pass through the capillary wall into the Bowman’s capsule.
How is water reabsorbed into the blood from the collecting duct?
Water is reabsorbed into the blood from the collecting duct by diffusion, following the reabsorption of salts, and controlled by ADH, which makes the walls of the collecting duct more permeable to water.
Why does selective reabsorption of glucose occur at the proximal convoluted tubule?
Selective reabsorption of glucose occurs at the proximal convoluted tubule because it is the only part of the nephron where the gates facilitating the active transport of glucose are found.
What is ADH’s role in regulating the blood’s water content?
ADH regulates the blood’s water content by controlling the tubules’ permeability to water, leading to more or less water being reabsorbed depending on the body’s needs, and ultimately producing either a large volume of dilute urine or a small volume of concentrated urine.
What does urine contain?
Urine contains water, urea, and ions, including excess mineral ions.
Explain the process of excretion in plants.
- Plants release oxygen and carbon dioxide through the stomata of leaves as waste products of metabolism.
- The rate of these processes is affected by the intensity of light, with oxygen being released in excess during the day when photosynthesis rates are higher than respiration rates, and carbon dioxide being released in excess at night when only respiration occurs.
