Test: Nutrition in Animals (UPSC Level) - UPSC MCQ

1. Villi - Increase surface area for absorption in the large intestine: Incorrect. Villi are present in the small intestine, not the large intestine. They increase the surface area for absorption of nutrients in the small intestine.

2. Assimilation - Process of using absorbed substances to build complex molecules: Correct. Assimilation involves the use of absorbed nutrients to form complex molecules necessary for the body.

3. Large Intestine - Main site for absorption of nutrients: Incorrect. The main site for absorption of nutrients is the small intestine. The large intestine primarily absorbs water and certain salts.

4. Egestion - Elimination of fecal matter through the anus: Correct. Egestion is the process of expelling undigested material and waste from the body through the anus.

Thus, pairs 2 and 4 are correctly matched.

1. Statement 1 is correct. Ruminants like cows and buffaloes possess a complex stomach with multiple chambers, one of which is the rumen. The rumen is the first chamber where the ingested grass is stored and undergoes partial digestion. This process results in the formation of cud, which is later regurgitated and chewed again to aid in the breakdown of fibrous plant material.

2. Statement 2 is correct. Amoeba is a single-celled organism that captures food using pseudopodia, which are extensions of its cell membrane. Once the food is engulfed, it is encased in a food vacuole where digestive enzymes break down the food into simpler substances that can be absorbed and used by the amoeba.

3. Statement 3 is correct. Horses and rabbits have a large caecum, a pouch connected to the junction of the small and large intestines. This structure contains bacteria that help in the digestion of cellulose, a major component of their plant-based diet. These bacteria are specialized in breaking down cellulose, which is otherwise indigestible by many animals, including humans.

All three statements accurately reflect the processes involved in the digestion of grass-eating animals and amoeba, making Option D the correct answer.

1. Esophagus: Correctly matched. The esophagus is a muscular tube that moves food from the mouth to the stomach through a series of rhythmic contractions known as peristalsis.

2. Stomach: Incorrectly matched. The stomach does not secrete insulin. Insulin is secreted by the pancreas, not the stomach. The stomach primarily produces mucus, hydrochloric acid, and digestive juices to aid in digestion.

3. Liver: Correctly matched. The liver secretes bile juice, which is essential for the digestion and emulsification of fats. Bile is stored in the gallbladder and released into the small intestine.

4. Small Intestine: Incorrectly matched. The small intestine does not produce hydrochloric acid. Hydrochloric acid is produced in the stomach. The small intestine receives digestive juices from the pancreas and liver and is responsible for the absorption of nutrients.

So, only pairs 1 and 3 are correctly matched, making the correct answer Option B: Only two pairs.

1. Starfish: Extends its stomach to externally digest food - Correct. Starfish are known to extend their stomachs out through their mouths to digest prey externally, particularly those with hard shells.
2. Human: Digestion begins in the stomach - Incorrect. In humans, digestion begins in the mouth where mechanical digestion occurs with the help of teeth and chemical digestion begins with saliva breaking down starches.
3. Starfish: Has a complete alimentary canal similar to humans - Incorrect. Starfish do not have a complete alimentary canal like humans. They have a simple digestive system that includes a mouth, stomach, and anus but lacks distinct sections like the small and large intestines in humans.
4. Human: Teeth are used for mechanical digestion - Correct. In humans, teeth play a crucial role in mechanical digestion by breaking down food into smaller pieces to facilitate further digestion.
Thus, out of the given pairs, only two pairs are correctly matched: Pair 1 and Pair 4.

1. Rumen: Initial chamber in ruminants for cellulose digestion - Correct. The rumen is indeed the first chamber in the stomach of ruminants like cows and buffaloes, where partial digestion of cellulose occurs with the help of bacteria.

2. Caecum: Structure in rabbits for digestion of cellulose - Correct. The caecum is a large sac-like structure in animals such as rabbits and horses that aids in the digestion of cellulose with the help of bacteria.

3. Pseudopodia: Projections used by Amoeba to capture food - Correct. Amoeba extends finger-like projections called pseudopodia to engulf food particles, forming a food vacuole.

4. Cud: Final stage of digestion in ruminants - Incorrect. Cud is not the final stage but rather partially digested grass that is regurgitated back to the mouth for further chewing.

Pairs 1, 2, and 3 are correctly matched. Pair 4 is incorrectly matched as cud refers to the regurgitated food that ruminants chew again, not the final stage of digestion.

The mucus produced in the inner lining of the stomach serves the crucial function of protecting the stomach lining. This protective layer helps prevent the stomach lining from being damaged by the acidic digestive juices and aids in maintaining the integrity of the stomach walls, ensuring proper digestion and overall gastrointestinal health.

Both statements are factually correct. Statement-I describes the feeding process of starfish, while Statement-II explains the general process of digestion in animals, without specifically relating to starfish. Hence, both statements are correct, but Statement-II does not directly explain Statement-I as they pertain to different aspects of feeding and digestion.

- Statement 1: Correct. Bees and hummingbirds feed by sucking nectar from flowers, which involves using specialized mouthparts to extract liquid food, classifying this mode of feeding as sucking.

- Statement 2: Incorrect. Snakes, such as pythons, do not chew their prey. Instead, they use a method known as "capturing and swallowing," where they swallow their prey whole after capturing it. Chewing is a method used by animals like ants to grind or break down food into smaller pieces.

- Statement 3: Correct. Aquatic animals, such as some species of fish and whales, utilize filter feeding to consume small particles or plankton floating in the water. This method involves filtering water to trap food particles.

Thus, only statements 1 and 3 are correct. Therefore, the correct answer is Option C: 1 and 3 Only.

Bees and hummingbirds primarily obtain their food by siphoning. Bees collect nectar from flowers using their specialized proboscis to suck the nectar out. Hummingbirds also feed on nectar by using their long, specialized beaks to sip the nectar from flowers. Siphoning is an efficient way for these animals to extract liquid food sources like nectar from flowers.

1. Statement 1 is correct. The movement of food in the oesophagus is indeed facilitated by peristalsis, which involves rhythmic contractions of the muscular walls of the oesophagus, pushing food towards the stomach. This process is a well-known mechanism of the digestive system.

2. Statement 2 is incorrect. While hydrochloric acid in the stomach creates an acidic environment that is crucial for activating digestive enzymes and killing bacteria, it does not play a direct role in the absorption of nutrients. Nutrient absorption primarily occurs in the small intestine.

3. Statement 3 is incorrect. Bile juice, secreted by the liver and stored in the gall bladder, is crucial for the digestion and emulsification of fats, not proteins. Proteins are primarily digested by enzymes such as pepsin in the stomach and further broken down by pancreatic enzymes in the small intestine.

Therefore, based on the analysis, the only correct statement is 1. Hence, the correct option is Option A: 1 Only.