Earthworm MCQ Test - Zoology, Class 11 - Class 11 MCQ

The gizzard is made of circular muscles and is internally lined by a cuticle. It acts as a grinder. After the gizzard, the food is pushed to the intestine where it is finally broken down into simpler compounds. 

• Increased Absorptive Area: The primary function of the typhlosole in earthworms is to increase the absorptive area of the intestinal epithelium. This allows for better absorption of nutrients from the ingested soil or organic matter.


• Enhanced Nutrient Absorption: The folds of the typhlosole provide a larger surface area for the absorption of water and nutrients, aiding in the digestion process.


• Improved Digestion: By increasing the absorptive area, the typhlosole helps in improving the efficiency of digestion in earthworms, allowing them to extract more nutrients from their food.


• Optimized Feeding: The presence of the typhlosole allows earthworms to efficiently extract nutrients from the soil, facilitating their role in nutrient cycling and soil health.

Therefore, the function of the typhlosole in earthworms is crucial for enhancing nutrient absorption, optimizing digestion, and aiding in their feeding habits.

• Function: Chloragogen cells in Pheretima and human liver cells both play a role in metabolism and storage of nutrients.


• Structure: Both Chloragogen cells and human liver cells have a granular cytoplasm and a large nucleus, indicating similarities in their cellular structure.


• Location: Chloragogen cells are found in the connective tissue of the intestine in Pheretima, while human liver cells are located in the liver tissue. However, both types of cells are involved in metabolic processes.


• Storage: Both types of cells store nutrients such as glycogen and lipids for energy production and regulation of blood sugar levels.


• Detoxification: Chloragogen cells in Pheretima and human liver cells are involved in detoxifying harmful substances by breaking them down and eliminating them from the body.

• The correct answer is the liver because Chloragogen cells in Pheretima perform functions similar to those of human liver cells.


• Both Chloragogen cells and liver cells are involved in metabolic processes, storage of nutrients, detoxification, and regulation of blood sugar levels.


• Therefore, the similarity between Chloragogen cells of Pheretima and human liver cells makes option B the correct answer.

• What are Chloragogen Cells?




• Chloragogen cells are specialized cells found in the body cavity of certain invertebrates, such as annelids and mollusks.


• They are typically located near the gut and serve various functions in the organism.




• Function of Chloragogen Cells




• Excretory Function: Chloragogen cells play a crucial role in excretion within the organism.


• Detoxification: These cells help in detoxifying harmful substances and waste products from the body.


• Storage: Chloragogen cells also store important nutrients and minerals for the organism.


• Immune Response: In some cases, these cells are involved in the organism's immune response and defense mechanisms.




• Conclusion




• Chloragogen cells are primarily responsible for excretory functions and detoxification within the organism, making them essential for maintaining overall health and well-being.

• Haemoglobin: Haemoglobin is a blood pigment found in earthworms. It is responsible for transporting oxygen from the lungs to the tissues.


• Haemocyanin: While haemocyanin is another type of blood pigment found in some invertebrates like mollusks and arthropods, it is not found in earthworms.


• Haematin: Haematin is a compound derived from haemoglobin and is involved in the breakdown of red blood cells. It is not a blood pigment found in earthworms.


• Melanin: Melanin is a pigment responsible for skin color in animals, but it is not a blood pigment found in earthworms.

Therefore, the correct answer is Haemoglobin, as it is the blood pigment found in earthworms.

• Blood Color: In earthworms, the blood is red due to the presence of hemoglobin, similar to human blood.


• Absence of Blood Corpuscles: Earthworms do not have blood corpuscles like red blood cells or white blood cells found in vertebrates.


• Blood Functions: The blood in earthworms primarily functions as a transport medium for nutrients, gases, and waste products.


• Respiratory System: Earthworms breathe through their skin, and the hemoglobin in their blood helps in the exchange of gases with the environment.


• Circulatory System: Instead of blood vessels, earthworms have a simple closed circulatory system with blood vessels and five pairs of 'aortic arches' that pump blood.

Therefore, in earthworms, the blood is red due to hemoglobin but lacks blood corpuscles, distinguishing it from the blood of vertebrates.

• Dorsal vessel: The dorsal vessel is not responsible for collecting blood from seminal vesicles and gonads.



• Ventral vessel: The ventral vessel is not involved in collecting blood from seminal vesicles and gonads.



• Subneural vessel: The subneural vessel does not play a role in collecting blood from seminal vesicles and gonads.



• Lateral oesophageal vessel: The lateral oesophageal vessel is responsible for collecting blood from seminal vesicles and gonads. It carries the blood to the respective organs for nourishment and oxygenation.

Earthworm exhibits a closed type of blood vascular system, consisting of blood vessels, capillaries and heart. In earthworm, in each of the segments 7, 9, 12 and 13 is found a pair of large, thick, muscular and rhythmically contractile vertical vessels, called hearts.

• Location: The dorsal blood vessel of an earthworm runs along the dorsal side of the body.


• Function: The dorsal blood vessel acts as the main pumping organ in the circulatory system of the earthworm.


• Structure: The dorsal blood vessel is a muscular tube that extends throughout the length of the earthworm's body.


• Segmentation: The dorsal blood vessel is responsible for distributing blood in the first 13 segments of the earthworm's body.


• Connection: The dorsal blood vessel is connected to the ventral blood vessel through a series of lateral vessels.

• Blood is red but haemoglobin is dissolved in plasma: This statement is true about earthworms. Earthworms do not have red blood cells like humans. Instead, their blood is red due to the presence of a protein called hemoglobin, which is dissolved directly in the plasma. This is known as hemoglobinemia.

Therefore, option B: Blood is red but haemoglobin is dissolved in plasma is the correct statement about earthworms.

• Direction: The flow of blood in the dorsal blood vessel of an earthworm is forwards.


• Explanation:
  
  
  
  • Earthworms have a closed circulatory system with a dorsal blood vessel that runs along the length of their body.
  
  
  • The blood in the dorsal blood vessel of an earthworm flows from the anterior (front) end to the posterior (back) end of the worm.
  
  
  • This forward flow of blood helps in transporting nutrients, oxygen, and waste products throughout the earthworm's body.
  
  
  
  

Therefore, the correct answer is option B: Forwards.

• Haemoglobin: Haemoglobin is a pigment found in the blood of vertebrates, responsible for carrying oxygen from the lungs to the tissues of the body. It is not found in the blood of Pheretima.



• Haemocyanin: Haemocyanin is a pigment found in the blood of some invertebrates, such as mollusks and arthropods. It is not found in the blood of Pheretima.



• Erythrocruorin: Erythrocruorin is a pigment found in the blood of annelids, such as earthworms (Pheretima). It is responsible for oxygen transport in these organisms.



• (1) or (3): The correct pigment found in the blood of Pheretima is Erythrocruorin, also known as Hemerythrin. Therefore, the correct answer is (1) or (3).

• Lateral oesophageal heart: It is a part of the circulatory system of insects, specifically in insects like grasshoppers, where it connects various vessels.


• Connections: The lateral oesophageal heart connects the dorsal vessel, supra oesophageal vessel, and ventral vessel in insects.


• Dorsal vessel: It is the main vessel that runs along the back of the insect and carries hemolymph (insect blood) towards the head.


• Supra oesophageal vessel: This vessel connects the head region of the insect with the rest of the body for the transport of nutrients and waste.


• Ventral vessel: It is the main vessel that runs along the underside of the insect and carries hemolymph towards the rear part of the body.


• Function: By connecting these vessels, the lateral oesophageal heart helps in the circulation of hemolymph throughout the insect's body, ensuring the transport of nutrients, oxygen, and waste products.

• Motor Neurons: These neurons are responsible for controlling muscle movements in the earthworm's body.


• Sensory Neurons: These neurons detect external stimuli such as light, temperature, and touch.


• Adjustor Neurons: These neurons help in coordinating the responses to stimuli by integrating sensory information and controlling motor output.


• All Neurons: Earthworms have a combination of motor, sensory, and adjustor neurons that work together to regulate various physiological processes in the organism.

Therefore, in earthworms, all types of neurons play essential roles in coordinating movements, responses to the environment, and overall physiological functions.

• Cerebral Ganglia: The cerebral ganglia, also known as the brain of the earthworm, is a structure located in the anterior end of the earthworm's body. It is responsible for coordinating various activities and functions in the worm's body, including the secretion of hormones.

• The cerebral ganglia in earthworms play a crucial role in regulating various physiological processes by secreting hormones.


• These hormones help in controlling growth, development, reproduction, and other essential functions in earthworms.


• By secreting hormones, the cerebral ganglia ensure proper coordination and communication between different parts of the earthworm's body.


• Overall, the cerebral ganglia serve as a control center for hormone secretion in earthworms, enabling them to maintain homeostasis and respond to environmental changes effectively.

Therefore, the correct answer is C: Cerebral ganglia.

• Location: These nephridia are found in specific segments of Pheretima.

• Candidtate Segments: The possible segments where pharyngeal nephridia can be found are:




• Segments 3, 4, and 5


• Segments 4, 5, and 6


• Segments 5, 6, and 7


• Segments 6, 7, and 8

• Correct Choice: The correct answer is option D - 4, 5, and 6.


• Explanation: The pharyngeal nephridia of Pheretima are located in segments 4, 5, and 6.

• Nephridia: Nephridia are the primary excretory organs in earthworms. They are tubular structures found in each segment of the earthworm's body. Nephridia filter waste products from the blood and coelomic fluid and excrete them through pores on the body surface.



• Flame cells: Flame cells are also present in earthworms, but they are not the main excretory organs. They are part of the protonephridial system and help in osmoregulation and excretion of metabolic wastes.



• Malpighian Tubules: Malpighian tubules are not found in earthworms. They are actually found in insects and other arthropods, where they play a role in excretion and osmoregulation.



• Skin: While the skin of the earthworm does play a minor role in excretion through diffusion of waste products, it is not considered a primary excretory organ in earthworms.

• Pharyngeal nephridia: These are nephridia located in the pharynx region of the organism.


• Septal nephridia: These are nephridia located in the septa or partitions of the body segments.


• Integumentary nephridia: These are nephridia that are associated with the integument or outer covering of the organism.


• Integumentary and pharyngeal nephridia: This option includes both integumentary and pharyngeal nephridia.

Among the options given, Integumentary nephridia are exonephric nephridia as they are associated with the outer covering of the organism. Therefore, option C is the correct answer.

• Responsible for excretion: Septal nephridia in earthworms play a crucial role in excretion by removing metabolic wastes from the body.


• Present in all body segments: Contrary to the statement, septal nephridia are not present in all body segments but are located in specific segments of the earthworm's body.


• To keep the surface moist: While septal nephridia are involved in excretion, their primary function is not to keep the surface moist but to maintain osmotic balance and remove nitrogenous wastes.


• Present in 4, 5, 6 segments: Septal nephridia are typically found in segments 15 to 19 of the earthworm's body, rather than segments 4, 5, and 6 as mentioned in the statement.

Therefore, the correct statement regarding septal nephridia of earthworms is that they are responsible for excretion, playing a vital role in maintaining the internal environment of the organism.

• Enteronephric nephridia in earthworm: These are the type of nephridia found in earthworms which are responsible for excretion. They are located in the intestine of the earthworm.


• Opening of nephridia: The enteronephric nephridia open into the intestine of the earthworm.


• Function: These nephridia help in the removal of metabolic wastes from the body of the earthworm by filtering the coelomic fluid and excreting it out through the intestine.


• Significance: The presence of enteronephric nephridia in the intestine of earthworms helps in maintaining the internal environment of the body by eliminating waste products.

• Location: The nephrostome is found in the septal nephridia of earthworms.


• Function: The nephrostome acts as a funnel-like structure that collects the excretory wastes from the coelomic fluid.


• Structure: The nephrostome is a ciliated funnel-shaped opening located at the anterior end of the earthworm's nephridia.


• Process: The nephrostome filters the coelomic fluid and directs it into the tubule of the nephridia for further processing and excretion.


• Importance: The nephrostome plays a crucial role in the excretory system of earthworms by facilitating the removal of metabolic wastes from the body.

• Option A: Intestine - The terminal ducts of septal nephridia in earthworms do not open in the intestine. The function of the intestine is primarily for digestion and absorption of nutrients.



• Option B: Paired septa excretory canals - This is the correct answer. The terminal ducts of septal nephridia in earthworms open into paired septa excretory canals. These canals help in the excretion of waste and maintenance of osmoregulation in earthworms.



• Option C: Paired supra intestinal excretory canals - The septal nephridia do not open in paired supra intestinal excretory canals. These canals are not involved in the excretory system of earthworms.



• Option D: Dorsal blood vessel - The terminal ducts of septal nephridia do not open in the dorsal blood vessel. The dorsal blood vessel is responsible for circulating blood in earthworms.

• Septal nephridia are excretory organs present in each segment of an earthworm.


• These nephridia are important for excreting waste and maintaining the osmotic balance in the body of the earthworm.


• The terminal ducts of septal nephridia connect to paired septa excretory canals, which help in the elimination of waste from the body.


• Understanding the excretory system of earthworms is crucial to comprehend their overall physiology and functioning in their environment.

• Pharyngeal nephridia: These are found in segments 4, 5, and 6 in Pheretima, not in segments 7 and 9.


• Lateral Hearts: These structures are present in segments 7 and 9 of Pheretima. They are responsible for pumping blood throughout the body.


• Spermatheca: Spermatheca is not a structure found in segments 7 and 9 of Pheretima. It is a reproductive structure present in segments 9 to 15.


• Lateral Oesophageal Hearts: These structures are not specifically found in segments 7 and 9 of Pheretima. They are located in segments 13 to 16 and are involved in pumping blood to the dorsal blood vessel.

Therefore, the correct answer is B: Lateral Hearts, as they are the structures found in segments 7 and 9 of Pheretima.

• Definition: Ureotelic organisms excrete urea as the primary nitrogenous waste product.


• Explanation: Earthworms are known to excrete urea as their primary nitrogenous waste product, making them ureotelic.


• Importance: Urea is less toxic than ammonia and requires less water for excretion, making it advantageous for earthworms to excrete urea.


• Comparison: Other types of nitrogenous waste excretion include ammonotelism (excreting ammonia) and uricotelism (excreting uric acid).

• Septal nephridia in earthworms: Septal nephridia are a type of excretory organ found in earthworms. They are located in the septa (dividing walls) between segments of the earthworm's body.



• Function of septal nephridia: Septal nephridia help in excretion by removing metabolic wastes from the earthworm's body.



• Discharge of excretory product: The excretory product produced by septal nephridia is discharged into the lumen of the intestine.



• Reason for discharge into the intestine: The lumen of the intestine provides a pathway for the excretory product to be eliminated from the earthworm's body. It allows for efficient removal of waste materials from the digestive system.



• Other options: The body cavity, pharynx, and outside on the body surface are not the correct locations for the discharge of excretory products. The lumen of the intestine is the specific site where the excretory product from septal nephridia is expelled.

• Both leave excretory products in intestine: Both septal nephridia and Malpighian tubules are excretory organs in different types of organisms. Septal nephridia are found in annelids, while Malpighian tubules are found in insects. Both of these structures excrete waste products that eventually end up in the intestine for elimination.

Therefore, the correct answer is option C: Both leave excretory products in intestine.

Earthworms are triploblastic and they have three prominent germ layers known as endoderm, mesoderm and ectoderm. The nephridia occur in pairs and performs a function similar to the vertebrate kidney. They remove metabolic wastes from an animal's body. The nephridia of the earthworm are of ectodermal origin. 

• Nephrotelic: Both man and earthworm excrete nitrogenous waste in the form of urea through their kidneys.


• Ammonotelic: Neither man nor earthworm excretes ammonia as their primary nitrogenous waste product.


• Ureotelic: Both man and earthworm excrete urea as their primary nitrogenous waste product.


• Urecotelic: This is not a correct term for describing the excretory system of man or earthworm.

Therefore, the correct answer is option C: Ureotelic.

• Spermatheca of Pheretima: The spermatheca of Pheretima is a structure for storing sperms in female earthworms.


• Function: It serves as a storage organ for sperms after copulation.


• Role in Reproduction: The spermatheca allows the female earthworm to store sperms from mating for later fertilization of eggs.


• Location: The spermatheca is located within the female reproductive system of the earthworm.


• Importance: The presence of a spermatheca ensures successful fertilization of eggs even when mating opportunities are scarce.

• Prostate glands: Prostate glands are not present in Pheretima. They are found in mammals and are responsible for producing prostatic fluid that helps in the transportation of sperm.



• Spermatheca: The spermatheca is the organ in Pheretima where sperms are stored. It is a sac-like structure located in the female reproductive system that receives and stores sperm after copulation.



• Testes: Testes are the male reproductive organs responsible for producing sperm. While sperm is produced in the testes, it is not stored there in Pheretima.



• Oviduct: The oviduct is part of the female reproductive system and is not involved in storing sperm. It is responsible for transporting eggs from the ovary to the uterus.

Therefore, sperms in Pheretima are stored in the spermatheca, which is a key organ in the female reproductive system of these organisms.