CBSE Questions for Class 11 Medical Biology Animal Kingdom Quiz 17 - MCQExams.com

• Monotremes are mammals but they lay eggs instead of giving birth to live young, like marsupials and placental mammals. 
• Monotremes are similar to reptilia in having shoulder girdle and egg. 
• Although they share some reptilian features, monotremes possess all the major mammalian characteristics, like air breathing, endothermy (i.e., they are warm-blooded), mammary glands, a furred body, a single bone in the lower jaw and three bones in the middle ear. 
• Hence, option A is correct.

• Marsupials are an infraclass of mammals found only in Australia region due to geographical isolation. 
• A distinctive characteristic, common to most species, is that the young are carried in a pouch. 
• They have a bifurcated penis, separated into two columns so that the penis has two ends corresponding to the females' two vaginas.
  
  Hence, option A is the correct answer.

$$\textbf{Correct option: A}$$

$$\textbf{Explanation for correct option:}$$

Option A:

$$\bullet$$ Bony fishes are also called Osteichthyes and they possess skeletons made up of bony material.

$$\bullet$$ These fishes have four pairs of gills (total eight) covered with operculum on each side.

$$\textbf{Explanation for incorrect options:}$$

Option B:

$$\bullet$$ All sponges are not marine, some of them are also freshwater.

$$\bullet$$ Collared cells are also called choanocytes which line the interior body of sponges and help in both digestion and respiration.

Option C:

$$\bullet$$ All mammals are viviparous except Platypus. Viviparous organisms give birth to young ones.

$$\bullet$$ All mammals possess a diaphragm which is a muscular partition between the thorax and abdominal cavity of the body, for breathing.

Option D:

$$\bullet$$ All reptiles possess scales on their epidermal layer.

$$\bullet$$ All reptiles possess three-chambered hearts except crocodiles.

$$\bullet$$ Most of the reptiles are cold-blooded i.e. they change their body temperature according to their surrounding temperature.

Hence the correct option is option A.

• The heart pumps only impure blood in sharks. Sharks have a two-chambered heart which is an S-shaped tube. It has an atrium and ventricle. The blood is pumped by the heart through the afferent branchial arteries to capillaries in the gills, where the blood is oxygenated). 
• The blood then flows through efferent branchial arteries, through the tissues of the body, and back to the heart in veins. Sharks have low blood pressures; the walls of the pericardium are rigid, creating suction within the pericardium to maintain the flow of blood. To circulate blood throughout their bodies, many sharks must swim continuously. 
• The blood flow is similar to humans because blood is pumped by the heart to the rest of the body by arteries and returned to the heart by veins. 
• A difference is that humans have 4-chambered hearts while sharks only have two chambers.

• Reptiles are cold-blooded, relying on external heat sources to raise their body temperature to a point necessary for activity. They are oviparous. Whereas mammals are warm-blooded, generating their heat internally, retaining it by insulation of fur and/or fat. Having a more consistent body temperature means a more continuous activity level, which means more fuel (food) is required to supply the energy necessary for this active lifestyle. 
• They possess the mammary gland, placenta during an embryonic developmental stage. They develop the young one inside the body and nourish their child through a vascular connection between mother and foetus. 
• Thus, the correct answer is option C.

• Cyclostomata have sucking and circular mouth without jaws. Median fins (appendages) are present but paired fins (appendages) are absent. Integuments are without scales.
•  In aves, forelimbs are modified into wings for flying and hind limbs are used for walking and running. The body is covered with feathers.skin is thin, dry and non-glandular. Lungs have air sacs. 
• In mammals, mammary glands are present for the nourishment of the young ones. Hairs are present on the body. They have 2 pairs of limbs. Pinnae are absent in monotreme (mammals that lay eggs). 
• Chondrichthyes have a persistent notochord, placoid scales as the exoskeleton and ventrally positioned mouth. Gill slits are not covered by an operculum.