Biology - B1 Understanding Ourselves

notes based upon level a - a* work with some c-d notes

HideShow resource information

Fit for life

glucose + oxygen --- carbon dioxide + water + energy = aerobic

glucose --- lactic acid + energy = anaerobic 

glucose is only partly broken down in anaerobic 

breathing rate = high so it can replace oxygen
heart rate = high so it can take lactic acid to live to be broken down

strength, stamina, agility, speed, flexibility = measuring fitness

blood pressure = mmHg
systolic = maximum pressure heart produces
diastolic = blood pressure between heartbeats

high blood pressure = small blood vessels bursting, brain damage, strokes
low blood pressure =  poor circulation, dizziness, fainting

1 of 10

What's for lunch?

meat + fish = first class protiens, contain amino acids, not made by body

protien defciency = kwashiorkor

RDA protien = 0.75 x body mass (kg)

BMI = mass (kg)
          height (m)
different diets for health/religious reasons, e.g jews don't eat pork

some are influenced by images in magazines
poor diets = risks of heart disease and diabetes

enzymes break down carbs, protien fats to smaller molecules, they diffuse through small intestine in to blood plasma(carbs/protiens) lymph(fats) and pass to cells

stomach makes hydrochloric acid to help enzyme pepsin work
bile helps emulsify fats because they are harder to digest and make a bigger surface area for enzymes to act on 

2 of 10

Keeping Healthy

mosquitoes = vectors, cause malaria, parasite gets its food from host (humans)
high sugar diet can cause diabetes
low vitamin c can cause scurvy
anameia = not enough iron
symptoms are caused by pathogen making toxins

pathogens have anitgens on thier surface
white blood cells make anti-bodies which lock on and destory pathogen
active immunity = pathogen invades body 2nd time, white blood cell make antibodies, destroying pathogen before symptoms occur - CAN LAST A LIFETIME
passive immunity = antibodies given in a vaccine, lasts only a short time

antibiotics attack bacteria and fungi but not viruses
if you use antibiotics alot, it can lead bacteria to become resistant

test new drugs = volunteers take drug, some take harmless drug (placebo)
blind trial = volunteers don't know what they're talking
double blind trial = doctors/volunteers don't know what they're taking 

3 of 10

Keeping in Touch (eyes)

binocular vision helps judge distance - range from eyes overlap

short or long sited = lens are wrong shape

red-green colour deficiency = inherited disease

accommodation =  focus on light by changing lens size

distant objects = ciliary muscles relax, tighten suspensory ligaments

near objects = ciliary muscles contract, suspensory ligaments slacken lens becomes fat, fatter the lense, more light it refract

as we get older, muscle gets less flexible making it hard to focus
glasses or contact lenses can correct some eye problems
cornea surgery can also correct vision - lasers change shape of cornea

CONCAVE - inwards like a cave
CONVEX - outwards like an oval

4 of 10

Keeping in Touch (neurones)

motor neurones carry impulse to muscles 

nerve impulse carried in axon of neurone

reflex arc 
stimulus -- receptor -- sensory neurone -- nervous system -- motor neurone -- effector -- response

touching a hot plate - spinal reflex arc

neurones are adapted to quickly carry and pass on impulses
- very long (upto 2meters)
- branched endings (dendrites) to pick up impulses
- covered in sheath made from fat, to stop impulses crossing over

signals travel from one neurone to another across a gap called the synapse 

5 of 10

Drugs and You

class A = heroin, methadone, cocaine, ectasy, LSD, magic mushrooms
class B = amphetamines, barbiturates
class C = anabolic steroids, cannabis, valium

nicotine acts as a stimulent = affects synapses 

alcohol is a depressant = affects brain, co-ordination and balance

cells lining trachea and bronchioles = epithelial cells (some have cilia)

tar collects in air sacs and aveoli deep inside lungs, irritate lung tissue and are carcinogens

tiny particulates in smoke also collect in lung tissue, blocking exchange of gases and reduce oxygen for rest of body

liver breaks down alcohol, alcohol kills livercells called cirrhosis

6 of 10

Staying in Balance (homeostatsis)

keeping a constant internal enviroment is called homeostatsis

sweat glands make sweat and needs heat energy to evaporate

dehydration = body gets too hot
hypothermia = body gets too cold

negative feeback controls body temp,
body is kept at 37 degrees celcius = optium temp for enzymes

hypothalamus is a gland in brain which detects temp change in blood

it triggers protective measures such as changing size of blood capillaries in skin
(vasoconstriction, vasodilation) 

7 of 10

Staying in Balance (hormones)

diabetes = pancreas doesn't make enough insulin

diabetes can be controlled by eating low sugar diet, or injection of insulin which lowers level of glucose in the blood

the size of insulin a person needs depends on diet and exercise

when glucose is too high, insulin converts some into glycogen which is stored in the liver

ovaries produce sex hormones when girls reach puberty, breasts grow, hips widen, periods start, because ovaries begin to release egg every month
testes produce male sex hormones, boys become muscular, grow facial hair and voice breaks, these are called secondary sexual characteristics

oestrogen and progesterone control the menstrual cycle, together they control ovulation

synthetic hormones are contraceptives which can stop ovulation   

8 of 10

Gene Control

the genetic code is in a chemical called DNA
the shape of dna is called a double helix (like a ladder)
the rungs of the ladder are made up of 4 bases, in different patterns which make you

the number of chromosomes are usually even, because they seperate when eggs and sperm are formed

your body is made up of one hundred million million cells 

every cell in your body has DNA, so even the cells in your hands, will have information about your eye colour.

the 4 bases of DNA are A, T, G and C, A ONLY links with T and G ONLY links with C
DNA codes for the making of a specific enzyme, these control cell reactions that produce different chemicals, therefore DNA controls what specific characteristics you have 

9 of 10

Who am I?

All humans have 46 chromosomes, arranged in pairs

one pair of these are the sex chromosomes, females have an identical pair (**), and males have non-identical pair (XY) each sperm carries either an X or Y

Humans are all different, they show variation
Variation = genes mixed up in gametes, and changes in genes called mutations

mutations change the DNA base sequence stopping the cell making the correct protein, some are harmful whereas some are good

characteristics = dominant over others than recessive ones 

monohybrid cross = one pair of characteristics, carried on a pair of chromosones, one carrying the dominant allele, one with the recessive allele

Alleles are different versions of the same gene. the dominant gene will always show up if the individual is heterozygous. 

10 of 10




great thanks, i clear;y have missed out various important facts on b1



its really good for last minute revision

Similar Biology resources:

See all Biology resources »