Question 2

Question: In frog, the Renal portal system is a special venous connection that acts to link:

Options:

A. Kidney and intestine

B. Kidney and lower part of body

C. Liver and intestine

D. Liver and kidney

Correct Answer: B

Year: NEET 2025

Solution: In frogs, there are specialized venous connections that serve specific functions. One such connection links the liver and intestine, known as the hepatic portal system. Another connects the kidney to the lower parts of the body; this is referred to as the renal portal system. The renal portal system specifically involves the transfer of blood from the lower regions of the body to the kidneys.

Step Solution:

1. Identify the anatomical structure in question: The Renal Portal System in a frog.

2. Define "Renal": Pertaining to the kidneys.

3. Define "Portal System": A system of veins that carry blood from one capillary bed to another before returning to the heart.

4. Recall the specific connection: In amphibians, the renal portal system carries blood from the posterior (lower) part of the body to the kidneys.

5. Select the matching option: Option B correctly identifies this link.

Difficulty Level: Easy

Concept Name: Renal Portal System

Short cut solution: Remember "Renal = Kidney" and "Portal = connection between two organs"; in lower vertebrates, kidneys process blood from the lower body before it hits the heart.

Question 12

Question: Nitrogenous waste is excreted in the form of pellet or paste by :

Options:

A. Ornithorhynchus

B. Salamandra

C. Hippocampus

D. Pavo

Correct Answer: D

Year: NEET-2022

Solution: Birds (Pavo) excrete nitrogenous wastes as uric acid in the form of pellet or paste with a minimum loss of water. Many bony fishes (like Hippocampus) and aquatic amphibians (like Salamandra) are ammonotelic in nature. Mammals (like Ornithorhynchus) mainly excrete urea and are called ureotelic animals.

Step Solution:

1. Recognize the mode of excretion: "Pellet or paste" indicates uricotelism (uric acid excretion).

2. Evaluate Option A: Ornithorhynchus (Platypus) is a mammal, thus ureotelic (excretes urea).

3. Evaluate Option B: Salamandra is an aquatic amphibian, thus ammonotelic (excretes ammonia).

4. Evaluate Option C: Hippocampus (Sea horse) is a bony fish, thus ammonotelic.

5. Evaluate Option D: Pavo (Peacock) is a bird; birds are uricotelic.

Difficulty Level: Medium

Concept Name: Uricotelism

Short cut solution: "Pellet/Paste" = Uric Acid = Birds/Reptiles. Pavo is the only bird on the list.

Question 26

Question: Select the option which shows correct matching of animal with its excretory organ and excretory product. 

Options:

A. (a)

B. (b)

C. (c)

D. (d)

Correct Answer: B

Year: KN NEET 2013

Solution: In salamander, kidneys (mesonepheric) are the excretory organs and the excretory matter is urea. In Labeo, mesonephric kidney is the excretory organ and excretion is ammonotelic. Peacock has metanephrid kidneys with excretory matter being uric acid. In housefly, excretion takes place by Malpighian tubules; excretory waste is uric acid chiefly.

Step Solution:

1. Analyze the matching requirements: Organ must match the animal and the waste product.

2. Check the data for Salamander: Uses kidneys and excretes urea (Ureotelic).

3. Check the data for Peacock: Should be uric acid (Uricotelic) via kidneys.

4. Check the data for Housefly: Should be Malpighian tubules and uric acid.

5. Conclusion: Based on the source, the correct pairing is provided in option (b).

Difficulty Level: Medium

Concept Name: Comparative Excretory Physiology

Short cut solution: Focus on the most distinct pairs: Insects = Malpighian tubules; Birds/Reptiles = Uric Acid.

Question 27

Question: Which one of the following options gives the correct categorization of six animals according to the type of nitrogenous waste they give out? 

Options:

A. (a)

B. (b)

C. (c)

D. (d)

Correct Answer: C

Year: Mains 2013

Solution: Those animals that excrete ammonia are called as ammonotelic, eg. aquatic amphibia. Those animals that excrete urea are called as ureotelic, eg. frog, humans. Those animals that excrete uric acid are called as uricotelic, eg. pigeon, lizards, and cockroach.

Step Solution:

1. Group animals by waste: Ammonia (needs much water), Urea (medium water), Uric Acid (low water).

2. Identify Ammonotelic: Aquatic animals like aquatic amphibians.

3. Identify Ureotelic: Terrestrial animals like adult frogs and humans.

4. Identify Uricotelic: Birds (pigeon), land reptiles (lizards), and insects (cockroach).

5. Match with Option C: This option correctly groups these categories.

Difficulty Level: Medium

Concept Name: Nitrogenous Waste Categorization

Short cut solution: Remember the environment: Aquatic = Ammonia; Terrestrial = Urea; Dry environment (Flight/Desert) = Uric Acid.

Question 30

Question: Which one of the following characteristics is common both in humans and adult frogs?

Options:

A. Four chambered heart

B. Internal fertilization

C. Nucleated RBCs

D. Ureotelic mode of excretion

Correct Answer: D

Year: Mains 2012

Solution: Excretion of urea is known as ureotelism. Ureotelic animals include cartilaginous fishes, semiaquatic amphibians such as frogs and toads, and all mammals (including humans).

Step Solution:

1. Compare Hearts: Humans have 4 chambers; frogs have 3. [Outside sources]

2. Compare Fertilization: Humans have internal; frogs generally have external. [Outside sources]

3. Compare RBCs: Human RBCs are non-nucleated; frog RBCs are nucleated. [Outside sources]

4. Compare Excretion: Both adult frogs and humans excrete urea.

5. Conclusion: Option D is the common trait.

Difficulty Level: Easy

Concept Name: Ureotelism

Short cut solution: Adult amphibians and mammals are both categorized as ureotelic to conserve water compared to their aquatic ancestors.

Question 34

Question: Uricotelic mode of excreting nitrogenous wastes is found in:

Options:

A. reptiles and birds

B. birds and annelids

C. amphibians and reptiles

D. insects and amphibians.

Correct Answer: A

Year: Mains 2011

Solution: Reptiles, birds, land snails and insects excrete nitrogenous wastes as uric acid in the form of pellet or paste with a minimum loss of water and are called uricotelic animals.

Step Solution:

1. Define Uricotelic: Excretion of uric acid to minimize water loss.

2. Analyze Option A: Both reptiles and birds are known to be uricotelic.

3. Analyze Option B: Annelids are not uricotelic. [Outside sources]

4. Analyze Option C/D: Amphibians are generally ammonotelic (larvae) or ureotelic (adults).

5. Conclusion: Select Option A.

Difficulty Level: Easy

Concept Name: Uricotelism

Short cut solution: Uric acid = Water conservation. This is a primary adaptation for birds (weight reduction) and reptiles (dry habitats).

Question 38

Question: Uric acid is the chief nitrogenous component of the excretory products of:

Options:

A. earthworm

B. cockroach

C. frog

D. man

Correct Answer: B

Year: 2009

Solution: Cockroach shows uricotelism. Animals which live in dry conditions have to conserve water. Therefore, they synthesize crystals of uric acid from ammonia. Uricotelic animals include most insects (e.g., cockroach), land reptiles, and birds.

Step Solution:

1. Identify the chemical: Uric acid.

2. Link to animal group: Uric acid is the primary waste for insects, birds, and reptiles.

3. Evaluate Earthworm: Often ammonotelic or ureotelic depending on moisture.

4. Evaluate Frog/Man: Both are primarily ureotelic.

5. Conclusion: Cockroach, being an insect, is uricotelic.

Difficulty Level: Easy

Concept Name: Uricotelism

Short cut solution: Insects = Malpighian tubules + Uric acid.

Question 54

Question: Nitrogenous waste products are eliminated mainly as:

Options:

A. urea in tadpole and ammonia in adult frog

B. ammonia in tadpole and urea in adult frog

C. urea in both tadpole and adult frog

D. urea in tadpole and uric acid in adult frog

Correct Answer: B

Year: 1991

Solution: Ammonia is highly soluble in water, so in aquatic animals e.g., tadpole of frog, the nitrogenous waste products are excreted in the form of ammonia. In terrestrial animals e.g., adult frog, these wastes are excreted in the form of urea.

Step Solution:

1. Identify the environment of a tadpole: Aquatic (water-rich).

2. Identify waste for aquatic larvae: Ammonia (requires lots of water to flush).

3. Identify the environment of an adult frog: Terrestrial/Semi-aquatic.

4. Identify waste for adult frog: Urea (to conserve more water than ammonia).

5. Match the sequence: Ammonia (tadpole) → Urea (adult).

Difficulty Level: Easy

Concept Name: Ontogenetic Shift in Excretion

Short cut solution: Water availability dictates waste: High water = Ammonia; Limited water = Urea.