Life Processes and Nutrition

Questions and Answers

Hydrogen-based molecules

Oxygen-based molecules

Carbon-based molecules (correct)

Nitrogen-based molecules

Assimilation

Digestion

Nutrition (correct)

Respiration

Digestion

Excretion

Respiration (correct)

Nutrition

Because not all cells are in direct contact with the surrounding environment Signup and view all the answers

Harmful waste products Signup and view all the answers

Storage of carbon-based molecules Signup and view all the answers

To convert energy sources to a uniform form usable for molecular movements and growth Signup and view all the answers

Uptake and transportation of food and oxygen Signup and view all the answers

Complexity of carbon sources Signup and view all the answers

Additional raw materials needed from outside Signup and view all the answers

Study Notes

Even when asleep, the body needs to maintain itself through life processes that prevent damage and breakdown.
These life processes require energy, which comes from outside the body in the form of food through nutrition.
Nutrition involves transferring energy from outside the body to the inside, and also provides raw materials for growth.

The body requires energy from outside sources, which can be varied and need to be broken down or built up in the body.
A series of chemical reactions are necessary to convert energy sources into a uniform energy form that can be used for maintaining living structures and growth.
Oxidising-reducing reactions are commonly used to break down molecules, and many organisms use oxygen from outside the body for this process.

Respiration is the process of acquiring oxygen from outside the body and using it to break down food sources for cellular needs.
Single-celled organisms do not need specific organs for respiration, but multi-cellular organisms require specialized tissues for this function.

In multi-cellular organisms, not all cells are in direct contact with the environment, so specialized tissues are needed for functions like food uptake and oxygen exchange.
This leads to the need for a transportation system in the body to carry food and oxygen from one place to another.

Chemical reactions that generate energy create by-products that are harmful to cells, and need to be removed from the body through excretion.
Excretion is essential to prevent damage and destruction of the organism, and maintain life.