Life Processes Chapter 5

Study Notes

Movement, growth, or other signs of activity may not be enough to confirm life
Even plants that don't visibly grow are still alive
Viruses don't show molecular movements until they infect a cell, raising questions about their status as living things
Organisms are complex, organized structures that require maintenance to survive
They need to constantly repair and maintain their structures, which are made up of molecules that need to be moved around

Maintenance is essential for organisms to prevent damage and breakdown
Energy is required for maintenance, obtained from outside the body
Nutrition is the process of transferring energy from food to the inside of the organism
Raw materials like carbon-based compounds are required for growth
Nutritional processes vary depending on the complexity of food sources
Energy sources are broken down or built up into a uniform source
Molecular movements and synthesis of necessary molecules require energy

Heterotrophic organisms depend on other organisms for energy
They have adapted to their environment, developing specialized structures and processes to obtain food

Nutrition is the process of obtaining nutrients from the environment
Single-celled organisms obtain nutrients through their entire surface
Multi-celled organisms rely on a complex system for obtaining nutrients
In humans, digestion starts in the mouth and ends with the anus
The digestive system breaks down food physically and chemically
Saliva contains amylase, which breaks down complex sugars
The stomach mixes food with digestive juices, including hydrochloric acid
The small intestine is where most digestion and absorption of nutrients occur
The large intestine reabsorbs water and forms faeces
Carbohydrates are broken down into simpler sugars, fats into fatty acids and glycerol, and proteins into amino acids