Obtaining Energy and Removing waste

Which of the following is the longest organ in the digestive system?

• Heart

• Small Intestine

• Large Intestine

• Esophagus

Answer explanation

The small intestine is the longest organ in the digestive system, measuring about 20 feet in length. In contrast, the large intestine is shorter, and the esophagus and heart are not part of the digestive system.

An activity like sleeping does not require energy.

• True

• False

Answer explanation

Sleeping does require energy for bodily functions like brain activity and maintaining homeostasis, making the statement false.

Absorption in the small intestine occurs through the walls of fingerlike projections called

• pharynx

• villi

• tongues

• hands

Answer explanation

Absorption in the small intestines occurs through the walls of villi, which are fingerlike projections that increase the surface area for nutrient absorption. The other options do not relate to this function.

What is the function of peristalsis?

• to move food through the digestive system

• to remove excess liquid from the body

• to chemically digest food to release nutrients

• to absorb nutrients into the blood

Answer explanation

Peristalsis is the wave-like muscle contractions that move food through the digestive system, ensuring it progresses from the esophagus to the stomach and intestines for further processing.

The esophagus is a tube that connects the

• mouth to the stomach

• mouth to the large intestine

• mouth to the small intestine

• stomach to the large intestine

Answer explanation

The esophagus is a muscular tube that connects the mouth to the stomach, allowing food to pass through after swallowing. Therefore, the correct answer is 'mouth to the stomach'.

Chemical digestion happens in the _______ with the help of gastric juice.

• stomach

• small intestine

• villi

• large intestine

Answer explanation

Chemical digestion primarily occurs in the stomach, where gastric juice breaks down food. The small intestine continues digestion and absorption, but the initial chemical digestion starts in the stomach.

Plants produce water vapor as a waste product.

• True

• False

Answer explanation

True. During photosynthesis, plants take in carbon dioxide and release oxygen, but they also lose water vapor through a process called transpiration, making water vapor a waste product.

What are the steps of the digestive system in order starting with food entering the mouth?

• Food enters the MOUTH, goes down the ESOPHAGUS, enters the STOMACH, enters the LARGE INTESTINE, enters the SMALL INTESTINE, waste is removed from the body.

• Food enters the MOUTH, goes down the ESOPHAGUS, enters the STOMACH, enters the SMALL INTESTINE, enters the LARGE INTESTINE, waste is removed from the body.

• Food enters the MOUTH, enters the STOMACH, goes down the ESOPHAGUS, enters the LARGE INTESTINE, enters the SMALL INTESTINE, waste is removed from the body.

Answer explanation

The correct order of the digestive system is: food enters the MOUTH, goes down the ESOPHAGUS, enters the STOMACH, then the SMALL INTESTINE, followed by the LARGE INTESTINE, and finally, waste is removed from the body.

When does the first step of digestion usually occur?

• when the organism discovers the food

• when the food is chewed

• when the food is swallowed

• when the nutrients are absorbed

Answer explanation

The first step of digestion occurs when the food is chewed, as this mechanical process breaks down food into smaller pieces, making it easier for enzymes to act on it during subsequent digestion stages.

Which type of digestion breaks down pieces of food into small molecules?

• mechanical digestion

• peristalsis digestion

• chemical digestion

• absorption digestion

Answer explanation

Chemical digestion is the process that breaks down food into small molecules through enzymatic reactions, allowing nutrients to be absorbed. In contrast, mechanical digestion involves physical breakdown, and peristalsis is a movement, not a digestion type.