Week 1

Question 1

What are the key concepts of the cell theory?

Answer 1

1. all living organisms are composed of one or more cells
2. cells are the basic unit of structure and organisation of all living organisms
3. cells arise only from previously existing cells

Question 2

What is the different between prokaryotes and eukaryotes?

Answer 2

Prokaryotic cells have a defining plasma membrane but their DNA is not contained in a nucleus an their cytoplasm is generally lacking organelles (e.g. bacteria, archaeans). Eukaryotic cells also have a plasma membrane and have organelles (e.g. human, animal,plant and fungal cells)

Question 3

What are the essential functions of life?

Answer 3

metabolism - the chemical reactions of the body
responsiveness - ability to sense changes in the environment and respond
movement - locomotion, propulsion and contractility
growth - increase in size of a body part or organism
digestion - breakdown of ingested foodstuffs
excretion - removal of wastes from the body
reproduction - cellular and organismal levels
maintaining boundaries - the internal environment remains distinct from the external environment

Question 4

What are the essential requirements for life?

Answer 4

• nutrients: for energy and cell building
• oxygen: for metabolic reactions
• water: provides environment for chemical reactions
• temperature: necessary for chemical reactions to occur at life-sustaining rates
• atmospheric pressure: required for proper breathing and gas exchange in the lungs

Question 5

Levels of structural organisation

Answer 5

Chemical - atoms combined to form molecules
Cellular - cells are made of molecules
Tissue - consists of similar types of cells
Organ - made up of different types of tissues
Organ system - consists of different organs that work closely together
Organismal - made up of organ systems

Question 6

Are structure and function related?

Answer 6

Structure and function are always related. For example, bones of the skull join tightly to from a rigid case that protects the brain, while bones of fingers are more loosely joined to allow a variety of movements.

Question 7

What is homeostasis?

Answer 7

Homeostasis is the ability to maintain a relatively stable internal environment in an ever-changing outside world. The internal environment of the body is in a dynamic state of equilibrium . Chemical, thermal, neural and hormonal factors interact to maintain homeostasis.

Question 8

What is negative feedback?

Answer 8

In negative feedback systems, the output decreases the original stimulus.

Question 9

What happenes when there is homeostatic imbalance?

Answer 9

Survival of cells is dependent on precise regulation of surrounding conditions (which is controlled by homeostatic mechanisms). If one or more components of the body lose their ability to regulate homeostasis, the normal balance of bodily processes may be disturbed. If homeostatic imbalance is moderate, a disorder or disease may occur; if it is sever, death may result.