Excretion in animals is the biological process through which waste products, particularly toxic nitrogenous wastes generated from metabolism, are removed from the body to maintain homeostasis. Different animals have evolved various excretory mechanisms based on their habitats and water availability. For instance, terrestrial mammals primarily excrete urea, requiring moderate water, while reptiles and birds excrete uric acid, which is less toxic and conserves water. Aquatic animals often excrete ammonia directly into the water. The excretory systems vary widely among species, including structures like nephrons in kidneys for vertebrates, protonephridia in flatworms, and Malpighian tubules in insects, all functioning to regulate water and solute balance while eliminating waste.
What is excretion in animals?
Excretion in animals is the biological process of removing waste products, particularly toxic nitrogenous wastes generated from metabolism, to maintain homeostasis in the body
What are the main types of nitrogenous waste excreted by animals?
Animals primarily excrete nitrogenous waste in three forms: ammonia, urea, and uric acid. These are classified as ammonotelic, ureotelic, and uricotelic animals, respectively
How do terrestrial mammals excrete nitrogenous waste?
Terrestrial mammals primarily excrete urea, which is less toxic than ammonia and requires moderate amounts of water for elimination
What excretory product do reptiles and birds produce, and why?
Reptiles and birds excrete uric acid, which is less toxic and conserves water, making it suitable for their arid environments
How do aquatic animals typically excrete nitrogenous waste?
Aquatic animals often excrete ammonia directly into the water, as it is highly soluble and can be diluted easily
What is the primary nitrogenous waste excreted by terrestrial mammals?
a) Ammonia
b) Uric acid
c) Urea
d) Creatinine
Answer: c) Urea
Which of the following animals primarily excretes uric acid?
a) Fish
b) Amphibians
c) Reptiles
d) Mammals
Answer: c) Reptiles
Aquatic animals typically excrete which form of nitrogenous waste?
a) Urea
b) Uric acid
c) Ammonia
d) Creatinine
Answer: c) Ammonia
What is the functional unit of the kidney responsible for excretion in vertebrates?
a) Glomerulus
b) Nephron
c) Malpighian tubule
d) Protonephridium
Answer: b) Nephron
Insects excrete waste primarily through which structure?
a) Kidneys
b) Malpighian tubules
c) Nephridia
d) Gills
Answer: b) Malpighian tubules