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B9: Coordination & Response
nerve impulse
an electrical signal that passes through neurons
CNS
central nervous system: brain & spinal cord
PNS
peripheral nervous system: receptor, motor neuron, sensory neuron
reflex arc
a stimuli affects the receptor
the sensory neuron carries impulse from receptor to CNS
relay neuron carries impulse across spinal cord
motor neuron carries impulse from CNS to effector
effector carries out response
voluntary action
involves brain
conscious thought, decision making
1 stimuli may have different responses
response is slower
involuntary action
does not involve brain
no conscious thought, automatic
response always the same
quick, rapid response
structure of the eye
ciliary muscle: controls thickness of lens
lens: focus light on retina
iris: controls how much light enter pupil
suspensory ligaments: hold lens
cornea: refracts light
nerve: send impulse to brain
retina: contains light receptors
pupil reflex: dim light
pupil dilates
radial muscle contract
circular muscle relax
pupil reflex: bright light
pupil contracts
radial muscle relax
circular muscle contract
accommodation: near object
suspensory ligaments slacken
ciliary muscle contracts
lens thicker
accommodation: far object
suspensory ligaments stretches
ciliary muscle relax
lens thinner
hormone
a chemical substance produced by a gland, travel through bloodstream to change the activity of an organ
adrenaline
adrenal gland
prepare body in ‘fight or flight’ mode
increase breathing/pulse rate,/glucose level, pupil dilates
insulin
produced in pancreas, act in liver
decrease blood glucose level
testoterone
male sex hormone
testes
oestrogen
female sex hormone
ovaries
effects of adrenaline
increase breathing rate: supply oxygen for respiration → release energy
increase pulse rate: blood carries oxygen to cells more quickly for respiration
increase blood glucose level: more glucose for respiration
pupil dilates: more light reaches retina, more information sent to brain
nervous system
short term
electrical impulses travel through neurons
not localised
fast
endocrine system
long term
chemical substances travel through bloodstream
localised
slower
homeostasis
the maintenance of a constant internal environment
negative feedback
when the concentration of a substance is too high/low, corrective mechanisms will be activated
when the concentration returns to normal, corrective mechanisms will be turned off
blood glucose level
insulin: converts glucose into glycogen → lowers blood glucose level
glucagon: converts glycogen into glucose → increase blood glucose level
these hormones are secreted in pancreas but act in liver
temperature regulation: too hot
skin hair rise
vasodilation: arterioles expand, allowing more blood to flow near to the skin
sweat gland produces sweat
temperature regulation: too cold
skin hair flatten
vasoconstriction: arterioles constrict, less blood flow through capillaries near skin
sweat gland stops producing sweat
gravitropism
response in which plants grow towards or away from gravity
phototropism
response in which plants grow away to towards the direction light is coming
growth hormone in plants
auxin
function of growth hormone in plants
made in tips of shoots
control tropisms
move to where it is required
causes plant cells to elongate
how phototropism works
auxin is made in tips of shoots only
auxin moves downwards and away from light
auxin causes cell elongation
when 1 side grows longer than the other, it causes the shoot to bend towards light
B8: Gas exchange & Respiration
inhalation
ribcage rise upwards & outwards
diaphragm contract & flatten
lung volume increase
air flows outside to inside
exhalation
ribcage falls downwards and inwards
diaphragm relax and curve upwards
lung volume decreases
air flows inside → outside
inspired air
nitrogen: 79: not used and produced by any body processes
oxygen: 21: used in repiration
carbon dioxide: 0.04
water vapour: variable
temperature: room temp
expired air
nitrogen: 79
oxygen: 16
carbon dioxide: 4: produced in respiration
water vapour: saturated: produced in respiration, evaporates from surface of alveoli
temp: 37
adaptations of alveoli
large surface area: maximise absorption as more gas molecules can diffuse at the same time
thin: only 1 cell thick, short diffusion distance, faster rate of absorption
covered with blood capillaries: good blood supply, gas diffuse in and out of blood
good ventilation with air: maintain high concentration gradient of oxygen and carbon dioxide
specialised cells
goblet cells: produce mucus to trap pathogens and dust particles
ciliated epithelial cells: tiny hairs sweep mucus out of the lungs and up the throat
found in trachea and bronchi
effects of breathing during exercise
increase rate of breathing
increase depth of breathing
effect of physical exercise on breathing
during exercise, muscles need more energy, which results in more respiration, and more carbon dioxide produced
carbon dioxide dissolve into blood and turn into carbonic acid→ makes blood acidic
brain receptors detect blood pH level, and send nerve signals to lung muscles
lung muscles would contract and relax faster→ increase breathing rate
diseases that smoking may cause
lung cancer, COPD
symptoms of COPD
difficulty in breathing, permanent lung damage
effects of dangerous chemicals produced by smoking
nicotine: additive; narrow blood vessels, increase blood pressure, increase risks of coronary heart disease
carbon monoxide: bind permanently with hemoglobin in RBC→ less oxygen supply for respiration
tar & smoke particles: lung cancer; chronic bronchitis: inflammation and excess mucus due to damaged cells; emphysema: alveoli walls destroyed→ reduce surface area for diffusion
definition of aerobic respiration
chemical reactions in cells that use oxygen to break down nutrient molecules and release energy
equation of aerobic respiration
glucose + oxygen → carbon dioxide + water
why do cells need to produce energy
grow/reproduce
muscle contraction
body temperature regulation
anaerobic respiration
chemical reactions in cells that break down nutrient molecules to release energy without using oxygen
use of anaerobic respiration
yeast anaerobic respiration: glucose→ ethanol + carbon dioxide
muscle cells: glucose→ lactic acid + energy
anaerobic respiration in bread making
produce carbon dioxide that is trapped in the dough to make the dough soft and spongy
oxygen debt
oxygen supply less than oxygen demand
repaying oxygen debt
during vigorous exercise, lactic acid build up in muscles and blood, causing oxygen debt
after exercising, we continue to have high breathing rate to have extra oxygen → break down lactic acid in liver
B7: Transport in plants & mammals
xylem
hollow tubes that run through roots, stem and to the lead, made from dead cells
role of xylem
transports water from the roots to leaves
role of phloem
transports sucrose & amino acids from areas where they are produced to areas where they are stored
root hair cells
function: absorb water and minerals
adaptation: they are many, have large surface area that increase rate of absorption
water uptake of plants
water first enter the root hair cells by osmosis
water crosses cortex of the root, cell by cell via osmosis
until it reaches xylem
water is then pulled up to stem and leaves through xylem vessels
water diffuses into mesophyll cells of leaves
transpiration(definition)
the loss of water vapour in plant leaves, by evaporation of water at the surface of mesophyll cells, followed by diffusion of water vapour into stomata
water is able to continuously flow up the plant due to
transpiration pull: the loss of water vapour in the leaves creates a tension that pulls water molecules up and maintain high water potential gradient
cohesion of water molecules: the water molecules tend to stick together and do not break apart, this helps to draw up a continuous column of water through xylem
factors affect transpiration rate
temperature: as temperature increases, water evaporates from the leaves faster, therefore rate of transpiration is increased
humidity: rate of transpiration is inversely proportional to humidity; the higher the humidity, the less steep the water potential gradient between inside and outside leaves, therefore rate of transpiration is slower
translocation
the movement of sucrose and amino acids in phloem from regions of production to regions of storage or where they are used
double circulatory system
blood passes heart twice in 1 circuit, 1 goes to lungs, 1 goes to the body
advantages of double circulatory system
separate oxygenated and deoxygenated blood
blood vessels flow to: liver
hepatic vein & hepatic artery
blood vessels flow to: kidney
renal vein & renal artery
blood vessel flow from stomach to liver
hepatic portal vein
blood vessel from head & arms to heart
superior vena cavab
blood vessel from body to heart
inferior vena cava
blood vessel from heart to body
aorta
cardiac cycle
atria contracts, pressure in atria increases, blood is pushed into ventricle (atrioventricular valves open)
ventricle contracts, atrioventricular valves close, semilunar valves open; blood is pushed out to the lungs and the body
heart relax and is filled with blood, semilunar valves close
artery
carries blood from heart to tissues
thick walls: withstand high pressure of blood & prevent blood vessels from bursting
small lumen: maintain high pressure
elastic wall: allow blood vessel to expand & recoil as blood pushes through
vein
have valve: prevent backflow of blood
big lumen: reduce resistance to blood flow
thin walls: maintain blood at low pressure
capillaries
very small lumen
1 cell thick
highly branched
blood contents
RBC
WBC
platelets
plasma
red blood cells
carries oxygen
contains hemoglobin
no nucleus: to fit in as much hemoglobin as possible
bi-concave shape: increase surface area for diffusion of oxygen
white blood cells
phagocytes: remove any microorganism enter body through phagocytosis
lymphocytes: produce bacteria
plasma
mostly water, contains many dissolved substances
platelets
help to clot blood and close wound
activated when blood vessels are damaged
effect of physical exercise on pulse rate
more glucose and oxygen needed for respiration to release energy
breathing rate increases to send oxygen to cells
heart pumps faster to send oxygen and glucose around the body
coronary heart disease: factors increase risks
diet high in fats
poor lifestyle
genetic factors
old age
coronary heart disease: the cause
coronary artery supplies blood to the heart muscle
plaque builds up in arteries
plaque explodes→ blood clot forms
blood clot blocks blood flow
heart muscle die→ heart attack
B1: Characteristics of living things
Movement
an action done by an organism that causes a change in position or place
respiration
chemical reactions that break down nutrients to release energy for metabolism
sensitivity
the ability to sense or detect stimuli in the internal or external environment to make appropriate responses
growth
the permanent increase in size and dry mass by increasing cell size or cell number
reproduction
the process of making more of the same kind of organism
excretion
the passing out of waste materials from metabolism, toxic substances in excess of the body
nutrition
the taking in of materials for energy, growth and development
B6: Animal Nutrition
balanced diet
a diet that contains all nutrients in correct proportions
factors affect dietary needs
age
gender
active lifestyle
carbohydrate
source: bread, rice, pasta
function: provide energy to body
malnutrition: too much carbohydrate: diabetes; too little: marasmus
protein
source: fish, meat, tofu
function: growth & repair
malnutrition: kwashiorkor: stunted growth
fats
source: oil, butter, cheese
function: store energy, keep body warm
malnutrition: cardiovascular disease, obesity
vitamin C
source: citrus fruits
function: make collagen
malnutrition: scurvy - bleeding gum, joint pain, skin wounds
vitamin D
source: sunlight, fish oil, egg yolk
function: absorb calcium
malnutrition: rickets: weak & soft bones
calcium
source: dairy products, soy beans
function: strengthen bones
malnutrition: rickets
iron
source: red meat, spinach
function: make hemoglobin
malnutrition: anemia: dizzy, pale skin
fibre
source: fruits & vegetables
function: help stretch muscles in the gut and push food along intestine
malnutrition: constipation
water
function: hydration, medium for blood transport, regulate body temp
malnutrition: dehydration