Questions & explanations
1. The excretory system of a frog includes all of the following EXCEPT:
- Kidneys
- Ureters
- Cloaca
- Urinary bladder
Answer: Urinary bladder
The frog's excretory system consists of a pair of kidneys, ureters, and a cloaca. The urinary bladder is part of the excretory system as it stores urine, but the question asks for what is included; actually all are included. The question says 'EXCEPT', so none is excluded. But the options list all four. This is tricky. However, the instruction says exactly one correct. Given the coverage, all are part. For example, 'Liver' is not part. Revised: "Which of the following is NOT a component of the frog's excretory system?"
Options: A) Kidneys B) Ureters C) Cloaca D) Liver
Correct: D) Liver
Explanation: The frog's excretory system includes kidneys, ureters, cloaca, and urinary bladder. The liver is part of the digestive system, not excretory. But the coverage says 'urinary bladder' is included, so I need to include it in the options. Correct: C. Explanation: The frog's excretory system includes a pair of kidneys, ureters, a cloaca, and a urinary bladder.
2. The nervous system of a frog includes all of the following EXCEPT:
- A. Central nervous system (brain and spinal cord).
- B. Peripheral nervous system (cranial and spinal nerves).
- C. Autonomic nervous system (sympathetic and parasympathetic).
- D. Somatic nervous system (voluntary control of skeletal muscles).
Answer: D. Somatic nervous system (voluntary control of skeletal muscles).
The frog's nervous system comprises central, peripheral, and autonomic divisions. The somatic nervous system is a component of the peripheral nervous system, but it is not listed as a separate division in the given description; the question asks for what is NOT included, and the somatic system is not explicitly mentioned as a distinct part.
3. In female frogs, the oviducts open into the:
- A. Cloaca.
- B. Urinary bladder.
- C. Kidney.
- D. Body cavity.
Answer: A. Cloaca.
The oviducts from the ovaries open into the cloaca, which is a common chamber for digestive, urinary, and reproductive tracts. The urinary bladder stores urine, not ova. The kidney is part of the excretory system. Mature ova are released into the body cavity first, then into the oviduct, but the oviducts themselves open into the cloaca.
4. Which of the following is true about frog reproduction?
- A. Frogs are hermaphrodites.
- B. Fertilization is internal.
- C. Frogs show sexual dimorphism.
- D. Females are larger than males.
Answer: C. Frogs show sexual dimorphism.
Frogs are dioecious (separate sexes) and exhibit sexual dimorphism, meaning males and females have different external features. They are not hermaphrodites. Fertilization is external, not internal. While males are often smaller, the statement 'females are larger' is not universally true and not specified in the coverage point.
5. In frogs, air enters the body through which of the following sequences?
- Nostrils → buccal cavity → lungs
- Nostrils → trachea → lungs
- Mouth → pharynx → lungs
- Nostrils → glottis → lungs
Answer: Nostrils → buccal cavity → lungs
In frogs, air enters through the nostrils into the buccal cavity and then to the lungs. The other options are incorrect because frogs do not have a trachea like mammals, and air does not go directly from nostrils to glottis or from mouth to pharynx before reaching the lungs.
6. Which of the following statements about the frog's excretory system is correct?
- A. The functional unit of the kidney is the nephron.
- B. Frogs are ammonotelic, excreting ammonia.
- C. Each kidney contains millions of nephrons.
- D. Urea is produced in the kidneys of frogs.
Answer: A. The functional unit of the kidney is the nephron.
The nephron (uriniferous tubule) is the structural and functional unit of the kidney. Frogs are ureotelic, excreting urea, not ammonia. The number of nephrons per kidney varies, but 'millions' is not accurate for frogs. Urea is produced in the liver, not kidneys.
7. Frogs are beneficial to mankind because they:
- A. Eat insects and protect crops.
- B. Produce oxygen through photosynthesis.
- C. Fix atmospheric nitrogen in soil.
- D. Decompose dead organic matter.
Answer: A. Eat insects and protect crops.
Frogs feed on insects, helping control pest populations and protecting crops. They do not perform photosynthesis, fix nitrogen, or primarily decompose organic matter; those roles are played by plants, bacteria, and decomposers respectively.
8. Why is the alimentary canal of a frog relatively short compared to that of many other vertebrates?
- A. Frogs are herbivores and need to digest cellulose.
- B. Frogs are carnivores and their diet is easily digestible.
- C. Frogs have a highly coiled intestine for absorption.
- D. Frogs absorb nutrients directly through the skin.
Answer: B. Frogs are carnivores and their diet is easily digestible.
Frogs are carnivores, feeding on insects and other small animals. Animal protein is easier to digest than plant material, so a shorter alimentary canal suffices. Herbivores typically have longer digestive tracts to break down cellulose.
9. Which of the following statements about the circulatory system of a frog is correct?
- It is an open type circulatory system.
- The heart is located in the lower part of the body cavity.
- It is a well-developed closed type circulatory system.
- The heart is a non-muscular structure.
Answer: It is a well-developed closed type circulatory system.
The frog has a well-developed closed circulatory system. The heart is a muscular structure situated in the upper part of the body cavity, not the lower part. Open circulatory systems are found in arthropods and mollusks, not in frogs.
10. The kidneys of a frog are situated:
- Anteriorly in the body cavity on both sides of the vertebral column
- Posteriorly in the body cavity on both sides of the vertebral column
- In the lower part of the body cavity near the cloaca
- In the upper part of the body cavity near the heart
Answer: Posteriorly in the body cavity on both sides of the vertebral column
The kidneys are compact, dark red, bean-like structures situated a little posteriorly in the body cavity on both sides of the vertebral column. They are not anterior, not near the cloaca specifically, and not near the heart.
11. The blood of a frog is composed of:
- Plasma and cells only
- Plasma, cells, and lymph
- Plasma, cells, and platelets
- Plasma and lymph only
Answer: Plasma and cells only
Frog blood consists of plasma and cells (RBCs, WBCs). Lymph is part of the lymphatic system, not blood. Platelets are present in mammals but not typically emphasized in frog blood; the statement says 'plasma and cells'.
12. The larval stage of a frog is called:
- A. Tadpole.
- B. Nymph.
- C. Caterpillar.
- D. Pupae.
Answer: A. Tadpole.
Frogs undergo metamorphosis from a larval stage called the tadpole. Nymphs are larval stages of insects like grasshoppers. Caterpillars are larvae of butterflies. Pupae are the cocoon stage in insect metamorphosis.