U1AOS2 Biological Systems Flashcards
Levels of structural organisation
Cell, tissue, organ, system, organism
Four basic tissue types
Muscle tissue, nervous tissue, epithelial tissue, connective tissue
Types of muscle tissue
Striated, cardiac, smooth
Striated muscle tissue
Contracts voluntarily
Attached to the skeleton
Cardia muscle tissue
Contracts involuntarily
Found in heart walls
Smooth muscle tissue
Contracts involuntarily
Surrounds organs
4 main types of nervous tissue
Bipolar interneuron
Unipolar sensory neuron
Multipolar motor neuron
Astrocyte (glial cell)
Epithelial tissues
Include all cells that form the interface between the body and external environment
Connective tissues
Fibrous tissues containing cells separated by an extra cellular matrix
The transpiration stream
Water moves from roots to leaves through xylem vessels through 4 main forces: osmosis, adhesion, transpiration and cohesion
Xylem vessels
Composed of dead, hollow cells with cell walls impregnated with lignin that makes the cells walls waterproof, hard and rigid
Adhesion
The attraction between water and some other surfaces. Water moves by adhesion up the xylem
Cohesion
The attraction of water molecules to one another due to their complimentary poles
Stomata
Tiny pores in the epidermis of a lead that allows the exchange of gases between inside and outside. Allows O2 and CO2 to be exchanged between the leaf and the air
Transpiration
As water is lost through the stomata, there is a negative pressure at the top of the xylem vessel. Works like a straw
Regulation of water loss
Each stoma is surrounded by a pair of guard cells that open and close to let water out or stop water from leaving
Translocation of sugars
Sugar moves into the phloem by active transport through membrane proteins or by simple diffusion through plasmodesmata. Moves down the phloem to the roots under pressure from osmosis
Phloem cells
Living cells that have no nucleus and accompanied by smaller companion cells
Purpose of the digestive system
To obtain nutrients from food that is ingested
Mechanical digestion
Food is broken down into smaller piece of food, increasing the SA:V
Chemical digestion
Changes what the food is made of due to a chemical reaction
Chemical digestion
Proteins are broken into amino acids by enzymes called proteases
Pathway from soil to leaf
Soil - root hairs - root cortex - endodermis - xylem in the root - xylem in the stem - xylem in the leaf - leaf intracellular spaces - into the atmosphere through stomata
Transport process in xylem
Transpiration stream (water and mineral ions)
Transport process in phloem
Translocation (sucrose, most hormones, mineral ions down)
Direction of xylem
One way, roots to leaves, powered by sun
Direction of phloem
Two way, powered by cellular respiration
What passes through a stomata?
Carbon dioxide, oxygen and water vapour
Enzyme to break down carbs
Amylase
Enzyme to break down protein
Protease
Enzyme to break down lipids
Lipase
Pituitary gland
Releases growth hormones and others, is the master gland
Thyroid gland
Releases thyroxine, regulates metabolism and growth
Hypothalamus gland
Releases many hormones and regulates many activities including temp regulation
Adrenal glands
Releases Adrenalin and cortisol, regulates the response to stress and metabolism
Pancreas glands
Releases insulin and glucagon, regulates blood glucose levels
Testes and ovaries glands
Releases testosterone, oestrogen and progesterone, regulates fertility and secondary sex characteristics
High glucose concentration
Beta cells in pancreas are stimulated to secrete insulin that converts glucose to glycogen and decreases the concentration of glucose in the blood
Low glucose concentration
Alpha cells in the pancreas secrete glucagon to stimulate the liver to convert glycogen to glucose. Increases blood sugar levels
Where does filtration occur
Bowman’s capsule
Where does reabsorbtion occur
Proximal tube mainly
What is the palisade?
Major site of photosynthesis
What reduces water loss?
Sunken stomata, thick cuticle and cylindrical leaves
Less water loss =
More likely to survive in dry environments
How are lipids transported?
Attached to proteins
