Digestive and Respiratory Systems of the Frog
The frog, Rana tigrina, solves two great physiological problems with remarkable economy: it must process food and it must obtain oxygen from both water and air. This quiz follows Lesson 3 of Structural Organisation in Animals and tests your grasp of the frog’s digestive canal from the buccal cavity to the cloaca, the glands that supply it, and the two modes of breathing — cutaneous and pulmonary respiration.
What you will be tested on
- The order of parts of the alimentary canal and why it is short in a carnivore
- The roles of the liver, gall bladder and pancreas, and the common bile duct
- The bilobed tongue, HCl and gastric juices, chyme, and the duodenum
- Villi and microvilli, the rectum and the cloaca
- Cutaneous and pulmonary respiration, including respiration during aestivation and hibernation
Work carefully through each question — the details of proportion and division of labour are what make this topic stick.
Q1. The alimentary canal of the frog is short mainly because the frog is:
Frogs are carnivores, and animal food requires a shorter intestinal length than bulky cellulose-rich plant material, so the intestine is reduced in length.
Q2. Which sequence correctly traces food through the frog's alimentary canal?
The mouth opens into the buccal cavity, which leads through the pharynx to the short oesophagus, then the stomach, intestine, rectum and finally the cloaca.
Q3. The two components of the frog's digestive system are:
The digestive system consists of the alimentary canal together with the digestive glands associated with it, such as the liver and pancreas.
Q4. Bile is secreted by the liver and stored in the:
The liver secretes bile, which is stored in the gall bladder before being released into the duodenum.
Q5. The pancreas of the frog produces pancreatic juice containing:
The pancreas is a digestive gland that produces pancreatic juice containing digestive enzymes, which digest carbohydrates and proteins.
Q6. Food is captured by the frog using the:
Food is captured by the bilobed tongue, which is flicked forward to secure insects and other small animals.
Q7. Digestion of food in the stomach takes place by the action of:
Digestion in the stomach occurs by the action of hydrochloric acid and gastric juices secreted from the walls of the stomach.
Q8. The partially digested food passed from the stomach to the duodenum is called:
Partially digested food is called chyme, and it is passed from the stomach to the first part of the small intestine, the duodenum.
Q9. The duodenum receives bile and pancreatic juices through the:
The duodenum receives bile from the gall bladder and pancreatic juices from the pancreas through a common bile duct.
Q10. What is the specific role of bile in the frog's digestion?
Bile emulsifies fat, while the pancreatic juices digest carbohydrates and proteins.
Q11. Absorption of digested food in the frog's intestine is carried out by:
Digested food is absorbed by the numerous finger-like folds in the inner wall of the intestine called villi and microvilli.
Q12. Undigested solid waste in the frog moves into the rectum and passes out through the:
The undigested solid waste moves into the rectum and passes out through the cloaca.
Q13. In water, the frog's respiratory organ is the:
In water, the skin acts as the aquatic respiratory organ, a process called cutaneous respiration, in which dissolved oxygen is exchanged by diffusion.
Q14. On land, which structures act as the respiratory organs of the frog?
On land, the buccal cavity, skin and lungs act as the respiratory organs, with respiration by lungs called pulmonary respiration.
Q15. During aestivation and hibernation, gaseous exchange in the frog takes place through the:
During aestivation and hibernation, gaseous exchange takes place through the skin.