biology unit 1 aos 2

waxy cuticle

• the outer layer of cells of the leaf is the epidermis

• epidermis has a waxy cuticle

• nearly waterproof and airproof

• dosent regulate water loss, provents it

stomata

• regulates water loss (transpiration)

• need to be open to allow for gas exchange

• when they are open, water is lost

• the balance between transpiration and photosynthesis is a compromise

roots

• plants regulate water absorption via the root systen

• the solute concentration gradient affects the rate of osmosis

• larger solute means higher rate of osmosis

• plants actively reabsorb mineral ions into the root hair system, water follows

factors that affect the rate of water loss

• number of stomata

• location of stomata

• surface area of the leaf

• humidity, water vapour in the air

• wind speed

homeostasis

• the maintenance of a stable internal environment within narrow limits, despite changes to the external environment

stimulus response model

• stimulus, receptor, control centre, effector, response

negative feedback

• when the response is the reverse of the stimulus

• most common feedback eg

• hen the body temp increases, cooling mechanisms are activated (sweating), decreases the body temp

positive feedback

• when the response reinforces the stimulus

• not very common eg

• urine contractions during child birth

thermoregulation

• the maintenance of core body temperature

• enzymes work best at 37 degrees

• high temps can cause heat stroke, low temps can cause hypothermia

• body temp is monitored by hypothalamus

when the body temp increases

• hairs on the arm lay flat

• sweating: when liquids evaporate from surfaces, they cool them, the glands secrete swear

• vasodilation: the blood cells thicken so more heat can go to the surface

when the body temp decreases

• arm hairs stand up
• shivering: muscle contractions, occurs quickly to release energy from gluecose
• vasoconstriction: the blood cells become thin so the body retains more heat

blood glucose regulation

• gluecose is needed for cells for cellular respiration
• maintained 70-140mg/100ml
• too much = hyperglycaemia (leakage in blood vessels)
• too little = hypoglycaemia (cells are starved of energy)

insulin

• when blood gluecose is too high
• gluecose receptors detect change
• beta cells in the pancreas produce insulin (in islet)
• causes glucose to move (lower blood glucose concentration)
• excess gluecose is stores as glycogen in the liver
• gluecose channels open up to allow gluecose into the cell

glucagon

• when blood gluecose levels are low
• gluecose receptors detect change
• alpha cells of the pancreas release glucagon
• triggers liver to convert glucagon back to glucose

water balance

• optimal osmolatiry = 285-295mosm/kg
• kidney and brain are primary organs involved
• water is essential

when water concentration is too low

• osmolatiry is too high
• triggers pituitary gland to release ADH
• ADH circulated blood until it reaches target cell
• increases permeability of collecting duct to water (absorbed more water, concentrates urine)
• hypothalamus is triggered, activates thirst response

when water concentration is too high

• osmolarity is low
• triggers pituitary gland to stop or reduce release of ADH
• causes less water to be reabsorbed from collecting duct
• more water is released in urine
• dilute urine produced by kidneys

type 1 diabetes

• caused by the bodies inability to regulate blood glucose levels
• homeostatic mechanisms do not work
• can lead to permanent organ damage
• two main types: type 1 and type 2
• the pancreas cannot produce insulin, beta cells are destroyed
• patients cannot maintain blood glucose concentration (causes metabolic changes)
• there is no cure, only treatment

hypoglycaemia

• when blood glucose concentration drops below tolerance range
• malfunction of blood glucose homeostasis
• if untreated, the brain will not receive enough glucose (can lead to seizures or unconsciousness)

causes of hypoglycaemia

• a person with diabetes taking too much insulin
• fasting or missing a meal
• a diet too low in carbohydrates
• strenuous activity
• drinking alchohol

signs of hypoglycaemia

• early: shaking, sweating, hunger, dizziness, weakness severe: confusion, slurred speech, loss of consciousness, fits, seizures

hyperthyroidism

• malfunction of the endocrine system
• thyroid hormone levels are not maintained at optimal level
• occurs when too much thyroid hormones are produced (means the body works harder and faster)
• most common cause of malfunctioning thyroid is graves disease

symptoms of hyperthyroidism

• fatigue, muscle weakness, rapid heartbeat, weight loss, trouble sleeping

treatment of hyperthyroidism

• anti-thyroid medication

organisation and specialisation

• cells, tissue, organ, system, organism

non-vascular plants

• plants that lack vascular tissue

vascular plants

• have vascular tissue, for conducting water and minerals through the plant there are non seed (ferns) and seeds (conifers and flowering plants)

shoot system

• main function to support the plant, connect the roots to leaves, can vary in height (usually above the ground)

root system

• main funcitions to anchor the plant to soil, absorb minerals and water, and storing products of photosynthesis

vascular tissue

• xylem and phloem which control water an nutrient movement

dermal tissue

• outer protective layer of the plant

ground tissue

• everything other than dermal and vascular

the xylem

• long tubelike structures that transport the majority of the water

• composed of tracheids and vessel elements

• wall are dead cells

• the walls are impregnated with lignin to provide strength

xylem - intake of water

• the root hair cells have long extensions that increase surface area

xylem - the movement of water

• transports water up through the transpiration system
• water is dissolved and minerals are absorbed via the root system, travel up the stem to the leaves, then they are released
• the transpiration stream is a passive process, relies on adhesion and cohesion of water molecules

xylem - the loss of water

• through evaporation that occurs through the stomata
• produces a pull on water molecules in the xylem vessel

stomata

• open: when the surrounding guard cells are turgid closed: when the surrounding guard cells are flaccid

phloem structure

composed of seive elements, connecting seive elements share a seive plate, companion cells surrounding the seive elements provide support

phloem function

• actively transports the products of photosynthesis via translocation

plant organs

roots, leaves, stems, flowers, fruits

epithelial tissue

• tissues made of tightly packed cells that line surfaces

• covers the surface of animals or organs

connective tissue

• binds and supports other tissues and organs, connects tissues to each other

muscle tissue (three types)

• smooth (involuntary, movement of substances through organs, controls airway diameter)

• cardiac (involuntary, pumps blood, produces rhythmic, coordinated contraction)

• skeletal (voluntary, movement of the body (physical), maintains posture, stabilises joints, produces heat during contractions (maintain body temp)

nervous tissue

• makes up central and peripheral nervous systems
• conducting nerve pulses in response to stimuli
• located in brain, spinal cord, and nerves

organs

• made up of more than one type of tissue
• consist of many types of cells (specialised)

systems

• coordinated so they can facilitate the supply of nutrients
• each system as a different structure and function
• each system needed for survival

structure of the digestive system

• consists of alimentary canal and organs

function of the digestive system

• digest food
• absorb nutrients
• eliminate wastes

alimentary canal tissues

• outer layer (connective)

• muscle layer (smooth, responsible for peristalsis)

• fluid connective tissue containing blood and lymphatic vessels

• innermost layer = more smooth muscle tissue, areola connective tissue

peristalsis

• the waves of contraction and relaxation in muscular walls

physical digestion

• mechanical breakdown of food into smaller peices
• increases SA:V of the food
• due to peristalsis
• also teeth and involved in mechanical breakdown

chemical digestion

• breaking the bonds in organic material with enzymes

chemical enzymes (digestion)

• carbohydrates to glucose

• proteins to amino acids

• lipids to fatty acids and glycerol

• nucleic acids to nucleotides

amylase in saliva

• crucial enzyme in human saliva, begins the digestive process by breaking down complex starch molecules

pH environments

• each enzyme has an optimal pH level

• mouth = pH 7.5 (neutral), optimal for salivary enzymes

• stomach = pH 2 (very acidic), pepsin enzymes in gastric juices break down proteins

• small intestine = pH 7-8, where many digestive enzymes are found

the chemical digestion process

• once food reaches the stomach, gastric juices are secreted (chyme)

• chyme enters small intestine via a spnicter

• the duodenum receives bile and pancreatic juice

• the secretions help neutralise stomach acid

absorption in the small intestine

• mainly occurs in the illuem
• contains folds with finger like villi protecting them
• helps slow the passage of food and increase the sa
• sa further increased from micro-villi
• glucose, nucleotides, and amino acids are absorbed into the blood stream

absorption in the large intestine

• where water absorption mainly occurs
• when water is absorbed, the remaining feces become solid
• feces contain insoluble and undigested material from the canal

egestion

• feces build up in the rectum

• when the rectum is full, feces are eliminated from the anus via egestion or defecation

structure of the endocrine system

• composed of glands that secrete hormones into the blood stream

function of the endocrine system

• the endocrine and nervous systems work together to maintain homeostasis
• produce and release hormones into the bloodstream to regulate this

endocrine glands

• ductless

• release hormones to travel to meet its target cell

examples of glands

• thyroid (affects metabolic rate, thyroxin)

• adrenal (adrenaline, cortisol, increases metabolic rate)

• pineal (melatonin, targets skin cells)

hormones

• chemical messengers that are produced and released

• travel through the bloodstream to reach a specific receptor in target cell

self regulating glands

• some glands are self regulating
• are not controlled by the pituitary and hypothalamus
• respond directly to changes in blood eg

pancreas

hypothalamus

• 'the control centre of the endocrine system'
• regulates main body functions
• releases hormones to suppress or stimulate the release of hormones from pituitary gland
• controls pituitary gland
• section of the forebrain veterbrates

pituitary gland

• pea sized organ
• known as the master gland
• regulates many glands through the release of hormones
• posterior lobe: extension on the hypothalamus, secreted ADH and oxytocin
• anterior lobe: biggest part of gland, regulates important bodily functions, controls other endocrine glands

structure of the excretory system

• kidneys, ureters, bladder, urethra

function of the endocrine system

• removal of chemical wastes (ammonia which is converted to urea)
• filters metabolic wastes
• eliminates them through urine to maintain homeostasis
• provents damage to the body

structure of the kidney

• bean shaped organ
• in upper posterior abdominal cavity
• two types of tissues

function of the kidney

• to remove excretory products from blood plasma and release urine
• contains nephrons

structure of the nephron

• tissues
• embedded in base connective tissue

filtration (nephron)

• in Bowmans capsule
• separates small molecules from blood
• water, ions, and small molecules are forced from the capillaries to capsule
• fluid created is called filtrate
• blood cells and proteins are too large to pass through
• passive process

reabsorption (nephron)

• in promixal convoluted tube, loop of henle, and distal convoluted tuble
• the process of reabsorbing important substances from the filtrate back into the blood
• proximal convoluted tuble: glucose and amino acids are actively transported back into the blood swell as sodium and chloride ions to create a larger surface area
• water is mainly absorbed by the loop of henle via osmosis

secretion (nephron)

• movement of waste back into filtrate for excretion in urine
• ammonium, potasium ions, hydrogen ions, are secreted in the distal convoluted tuble
• occurs simultaneously with absorption
• the filtrate becomes more concentrated