(a) (i) What is meant by a 'balanced' diet? A balanced diet is one that contains all the food types in correct or suitable proportions necessary for maintaining health - Leaving Cert Biology - Question 13 - 2010

Autotrophic nutrition is the process whereby organisms synthesize food from simple inorganic substances like carbon dioxide, thus producing their own food. In contrast, heterotrophic nutrition involves organisms that cannot produce their own food and must consume organic substances for energy, relying on other sources.

1. Incisors: Their primary role is to cut food.
2. Molars: They are responsible for chewing and grinding food.

Peristalsis is defined as the rhythmic muscular contractions that occur in the walls of the alimentary canal, facilitating the movement of food through the digestive tract.

1. Mechanical changes: The food is churned, which helps mix it and break it down.
2. Chemical changes: The food undergoes pH alterations and is broken down by gastric acid and digestive enzymes into simpler molecules, particularly peptides.

The pH of the stomach contents ranges from approximately 0 to 3, indicating a highly acidic environment.

The partially digested food moves into the duodenum, which is the first section of the small intestine.

1. One role of the pancreas in digestion is to produce enzymes that aid in the breakdown of food.
2. The gall bladder's primary role is to store bile and release it into the small intestine to help digest fats.

The digested food enters the blood from the small intestine.

The blood vessel that carries the digested food to the liver is the hepatic portal vein.

1. The liver generates heat and stores vitamins.
2. It also plays a crucial role in the detoxification of poisons and the regulation of cholesterol.

1. These bacteria synthesize essential vitamins that the body needs for various functions.
2. They out-compete harmful pathogens, thus helping to complement our immune system.