Question

Identify the correct statement/s regarding class aves.
1. Forelimbs are modified into wings and hindlimbs are modified for walking and swimming.
2. Heart is completely four-chambered.
3. They are homeotherms.
4. They are oviparous and development is direct.

• A. Both 1 and 3
• B. Both 1 and 4
• C. 1, 2 and 3
• D. All are correct

Answer 1

The Correct Option is D

Let's evaluate each statement regarding Class Aves:

Forelimbs are modified into wings and hindlimbs are modified for walking and swimming:

• This is correct. In birds, the forelimbs are modified into wings, which are used for flight. The hindlimbs are adapted for various purposes, including walking (in terrestrial birds) or swimming (in aquatic birds like penguins).

Heart is completely four-chambered:

• This is correct. Birds have a four-chambered heart, which allows for efficient separation of oxygenated and deoxygenated blood, supporting their high metabolic rate.

They are homeotherms:

• This is correct. Birds are homeothermic (also known as endothermic), meaning they maintain a constant body temperature, irrespective of the external environment.

They are oviparous and development is direct:

• This is correct. Birds lay eggs (oviparous) and undergo direct development (meaning the young birds resemble adults after hatching).

All the statements regarding Class Aves are correct.

The correct answer is (D) : All are correct.

Answer 2

We need to evaluate each statement regarding the characteristics of the class Aves (birds). 

1. "Forelimbs are modified into wings and hindlimbs are modified for walking and swimming."
   • The modification of forelimbs into wings (usually for flight, though some birds are flightless) is a defining feature of birds. This part is correct.
   • The hindlimbs are typically adapted for various forms of locomotion depending on the species, including walking, perching, hopping, running, wading, or swimming (often with webbed feet). This part is also correct.
   • Overall, statement 1 is correct.
2. "Heart is completely four-chambered."
   • Birds, like mammals, possess a completely four-chambered heart (two atria and two ventricles). This allows for efficient, complete separation of oxygenated and deoxygenated blood, supporting their high metabolic rate needed for flight and endothermy.
   • Statement 2 is correct.
3. "They are homeotherms."
   • Birds are endothermic homeotherms, commonly known as warm-blooded. They generate their own metabolic heat (endothermy) and maintain a stable, high internal body temperature regardless of the external environment (homeothermy).
   • Statement 3 is correct.
4. "They are oviparous and development is direct."
   • All birds reproduce by laying amniotic eggs with hard calcareous shells; they are oviparous. This part is correct.
   • Development is direct, meaning the young hatch from the egg as small versions of the adult bird (chicks or nestlings) and undergo growth, without a distinct larval stage or metamorphosis. This part is also correct.
   • Overall, statement 4 is correct.

Since all four statements (1, 2, 3, and 4) accurately describe characteristics of the class Aves, the correct option is that all are correct.

Therefore, the answer is: All are correct.