Excretion in Other Animals Practice Questions
20 free Excretion in Other Animals practice questions for the NCERT Biology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which excretory product is most commonly eliminated by aquatic animals?
- A Uric acid
- B Urea
- C Ammonia
- D Creatinine
Correct answer: Ammonia
Aquatic animals eliminate ammonia directly into surrounding water. Ammonia is highly toxic but easily diluted in aquatic environments.
Animals that excrete ammonia as the main nitrogenous waste are called:
- A Ureotelic animals
- B Uricotelic animals
- C Ammonotelic
- D Osmoconformers
Correct answer: Ammonotelic
Ammonotelic animals excrete ammonia as their primary nitrogenous waste. This is common in aquatic invertebrates and bony fishes, where ammonia is easily diluted in the surrounding water.
Which group of animals is typically ureotelic?
- A Insects
- B Birds
- C Mammals
- D Reptiles
Correct answer: Mammals
Mammals primarily excrete nitrogenous waste in the form of urea. Urea is less toxic than ammonia and requires moderate water for elimination.
Uric acid excretion is an adaptation mainly seen in:
- A Freshwater and marine fishes
- B Terrestrial amphibians
- C Birds and reptiles
- D Semi-aquatic mammals
Correct answer: Birds and reptiles
Birds and reptiles excrete uric acid to conserve water, as uric acid is less soluble and can be excreted as a semi-solid paste with minimal water loss.
Which excretory structure is characteristic of flatworms?
- A Nephridia
- B Malpighian tubules
- C Flame cells
- D Green glands
Correct answer: Flame cells
Flatworms possess flame cells as excretory units. These help in osmoregulation and waste removal.
Nephridia are the excretory organs of:
- A Arthropods
- B Segmented annelids
- C Molluscs
- D Echinoderms
Correct answer: Segmented annelids
Annelids such as earthworms possess nephridia. These tubular structures filter metabolic waste from body fluids and are important for osmoregulation.
Malpighian tubules are associated with excretion in:
- A Fishes
- B Molluscs
- C Insects
- D Amphibians
Correct answer: Insects
Insects use Malpighian tubules to remove nitrogenous wastes. These tubules open into the digestive tract.
The excretory organs of crustaceans are known as:
- A Flame cells
- B Nephridia
- C Green glands
- D Coxal glands
Correct answer: Green glands
Crustaceans like prawns possess green glands for excretion. These glands are located near the base of antennae.
Which nitrogenous waste requires the least amount of water for excretion?
- A Ammonia
- B Urea
- C Uric acid
- D All require equal water
Correct answer: Uric acid
Uric acid requires minimal water for elimination. This is advantageous for animals living in dry environments.
Insects conserve water during excretion mainly by:
- A Excreting dilute urine
- B Producing ammonia
- C Reabsorbing water in rectum
- D Increasing body surface area
Correct answer: Reabsorbing water in rectum
In insects, water is reabsorbed in the rectum before waste elimination. This conserves water efficiently.
Which animal group shows a transition from ammonotelism to ureotelism during its life cycle?
- A Terrestrial reptiles
- B Arboreal birds
- C Amphibians
- D Aquatic mammals
Correct answer: Amphibians
Amphibians excrete ammonia in the larval (aquatic) stage and switch to urea as adults when they move to land. This transition reflects their adaptation to both aquatic and terrestrial life.
Excretion in sponges occurs mainly by:
- A Specialized flame cells
- B Simple diffusion across body surface
- C Segmental nephridia
- D Contractile vacuoles in choanocytes
Correct answer: Simple diffusion across body surface
Sponges lack specialized excretory organs. Metabolic wastes diffuse directly across the cell surface into the surrounding water.
Which excretory product is least toxic?
- A Ammonia gas
- B Dissolved urea
- C Uric acid
- D Creatinine salts
Correct answer: Uric acid
Uric acid is the least toxic nitrogenous waste. Its low solubility allows safe storage and semi-solid elimination with minimal water loss.
Coxal glands function as excretory organs in:
- A Flying insects
- B Arachnids
- C Aquatic annelids
- D Marine molluscs
Correct answer: Arachnids
Arachnids such as spiders possess coxal glands located at the base of the legs. These organs aid in the removal of metabolic wastes.
Which factor most strongly influences the type of nitrogenous waste excreted by animals?
- A Overall body size of the animal
- B Dietary composition and protein intake
- C Availability of water in the habitat
- D Reproductive strategy employed
Correct answer: Availability of water in the habitat
Water availability in the habitat is the primary factor determining the form of nitrogenous waste an animal excretes. Aquatic animals excrete ammonia, whereas terrestrial animals produce less toxic, less soluble urea or uric acid.
Molluscs primarily use which structure for excretion?
- A Flame cells
- B Metanephridia (nephridia)
- C Malpighian tubules
- D Green glands
Correct answer: Metanephridia (nephridia)
Molluscs possess metanephridia for excretion. These tubular organs filter wastes from the body fluids and aid in osmoregulation.
Which excretory product is eliminated as a semi-solid paste?
- A Ammonia
- B Urea
- C Uric acid
- D Creatinine
Correct answer: Uric acid
Uric acid is excreted as a semi-solid paste. This reduces water loss and is typical of birds and reptiles.
Contractile vacuoles in protozoans primarily help in:
- A Intracellular digestion
- B Aerobic respiration
- C Osmoregulation
- D Asexual reproduction
Correct answer: Osmoregulation
Contractile vacuoles expel excess water from the cell, maintaining osmotic balance. This is especially important for freshwater protozoans, which constantly take in water by osmosis.
Which of the following animals is ammonotelic?
- A Human adult
- B Frog larva
- C Desert lizard
- D Sparrow
Correct answer: Frog larva
Frog larvae (tadpoles) live in water and excrete ammonia directly into the surrounding medium. This allows rapid diffusion of the toxic waste before it accumulates.
The main advantage of urea over ammonia as an excretory product is:
- A Greater solubility in water
- B Significantly lower toxicity to tissues
- C Requires no metabolic energy for synthesis
- D Complete insolubility in blood
Correct answer: Significantly lower toxicity to tissues
Urea is far less toxic than ammonia, allowing it to be safely transported in the bloodstream and stored in the body before excretion. This makes urea a safer waste product for terrestrial animals.