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Question 1

Describe the key elements of cell theory

Answer 1

all living organisms are composed of 1 or more cells
cells are the basic unit of structure + organisation of all living organisms
cells only arise from preexisting cells

Question 2

Compare + contrast prokaryotic / eukaryotic cells

Answer 2

Prokaryotic: no nucleus, lacks membrane-bound organelles

Eukaryotes - nucleus, membrane bound organelles, linear DNA

Question 3

Name 3 main structural features of a cell + describe their basic functions

Answer 3

Cell membrane: allowing cells to be self-contained + forming a barrier
Cytoplasm: intracellular solution containing organelles + structures for functioning
Nucleus: control centre of the cell, controlling activity + life cycle

Question 4

List the essential functions of life + requirements to support these

Answer 4

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

Question 5

Outline the structural levels of organisation of the human body

Answer 5

Chemical - atoms combined to form molecules
Cellular - molecules combine to form cells: the basic structural + functional units of an organism
Tissue - groups of cells + surrounding materials working together to perform a similar function
Organ - 2 or more different tissues joined together, performing a specific function
Organ system - different organs working together to perform a common function
Organismal - a living individual made up of the functioning organ systems

Question 6

Explain with examples how structure + function are related

Answer 6

Skull bones tight for protection but hands lose for movement
Scrotum hangs outside to keep sperm lower temp
2 eyes = stereoscopic vision

Question 7

Explain homeostasis + describe the basic components of negative feedback system

Answer 7

• Ability to maintain a relatively stable internal environment in an ever-changing outside world. Chemical, thermal, neural + hormonal factors interact to maintain homeostasis.

Negative feedback: output decreases original stimulus

Question 8

describe the structure + function of the plasma membrane

Answer 8

lipid bilayer: polar heads + non-polar tails

Selective barrier, flexible outer surface, appropriate intracellular environment, communiation

Question 9

describe the fluid mosaic model

Answer 9

Molecular arrangement of plasma membrane is constantly moving.
Some proteins float freely, others are anchored.
Fluidity depends on lipid saturation + cholesterol

Question 10

Describe microfilaments, intermediate filaments + microtubules

Answer 10

Microfilaments:

• thinnest
• actin + myosin
• edge of cell
• generate movement + physical support

Intermediate filamants

• several strong proteins; found in parts of cell subject to stress
• stabilise organelles

Microtubules

• thickest
• long, branched, hollow tubes (mainly tublin)
• assembly begins @ centrosome
• helps determine cell shape
• movement of organelles, cilia, flagella, chromosomes during cell division

Question 11

describe cilia, microvilli + flagella

Answer 11

Cilia: move fluids along cell surface
- microtubules

Flagella