Circulatory and Excretory Systems of the Frog
The frog is a small animal with a demanding physiological brief: it must move oxygen, nutrients, hormones and waste through a body that alternates between pond water and dry land. Two systems carry that burden — the closed vascular system and the excretory system.
This quiz tests your command of the details that make the frog’s internal logistics distinctive:
- The three-chambered heart, its pericardium, sinus venosus and conus arteriosus
- The hepatic and renal portal systems
- Nucleated RBCs and how lymph differs from blood
- Kidneys, ureters, cloaca and the thin-walled urinary bladder
- Uriniferous tubules and the frog’s ureotelic habit
- Key differences between male and female frogs
Read each question carefully — several frog features are easy to confuse with those of mammals. Precision is the whole point.
Q1. The vascular system of the frog is best described as:
The vascular system of the frog is well-developed and of the closed type, meaning blood remains within vessels throughout its circuit and is propelled by a muscular pump.
Q2. How many chambers does the frog's heart possess, and what are they?
The frog heart has three chambers — two atria and one ventricle — and is covered by a membrane called the pericardium.
Q3. The triangular structure that joins the right atrium and receives blood through the vena cava is the:
The sinus venosus is a triangular structure that joins the right atrium and receives blood through the major veins called the vena cava.
Q4. On which side of the heart does the ventricle open into the sac-like conus arteriosus?
The ventricle opens into a sac-like conus arteriosus on the ventral side of the heart, from which blood passes into the arterial system.
Q5. The special venous connection between the liver and the intestine in the frog is called the:
The special venous connection between liver and intestine is the hepatic portal system, while the connection between kidney and lower parts of the body is the renal portal system.
Q6. Which statement about the red blood cells of the frog is correct?
Frog RBCs (erythrocytes) are nucleated and contain the red coloured pigment haemoglobin.
Q7. How does lymph differ from blood in the frog?
The lymph is different from blood because it lacks a few proteins and RBCs.
Q8. The lymphatic system of the frog consists of:
The lymphatic system consists of lymph, lymph channels and lymph nodes, while the blood vascular system involves heart, blood vessels and blood.
Q9. The excretory system of the frog consists of:
The excretory system consists of a pair of kidneys, ureters, cloaca and urinary bladder.
Q10. The structural and functional units of the frog kidney are called:
Each kidney is composed of several structural and functional units called uriniferous tubules or nephrons.
Q11. In male frogs, the ureters act as which duct?
In male frogs the ureters act as the urinogenital duct, which opens into the cloaca.
Q12. In female frogs, how do the ureters and oviducts open into the cloaca?
In females the ureters and oviduct open separately in the cloaca, unlike the male where the ureters act as a urinogenital duct.
Q13. The frog is described as ureotelic because it:
The frog excretes urea and thus is a ureotelic animal. Excretory wastes are carried by blood into the kidney where they are separated and excreted.
Q14. Where is the thin-walled urinary bladder of the frog located?
The thin-walled urinary bladder is present ventral to the rectum, which also opens in the cloaca.
Q15. Which of the following correctly describes the frog's kidneys?
The kidneys are compact, dark red and bean-like structures situated a little posteriorly in the body cavity on both sides of the vertebral column.