B1- Understanding organisms Flashcards
What is blood pressure measured in?
Millimetres of mercury
(mmHg)
What is systolic pressure?
Maximum pressures the heart produces
What is diastolic pressure?
Blood pressure between heart beats
What can **increase **blood pressure?
- stress
- high alcohol intake
- smoking
- being overweight
What can **decrease **blood pressure?
- regular exercise
- balanced diet
What can high blood pressure cause?
- Blood vessels can burst
- Leading to damage to the brain (stroke)
- Or kidney damage
What can low blood pressure cause?
- Dizziness and fainting as blood supply to the brain is reduced
- Poor **circulation **to other areas such as fingers and toes
Define fitness.
The ability to do physical activity
Define health.
Being free from diseases such as those caused by **bacteria **and viruses
What can general fitness be measured by?
Cardiovascular efficiency
What else can your fitness be measured by?
- strength
- flexibility
- stamina
- agility
- speed
How can smoking increase blood pressure?
**Carbon monoxide **causes blood to carry less oxygen. So, the heart rate increases and tissues do not receive enough oxygen.
Also, nicotine directly increases heart rate.
What does carbon monoxide do to haemoglobin in the blood?
It combines with it, preventing it from combining with oxygen, so less oxygen is carried around the body
What is heart disease caused by?
Restricted blood flow to the heart muscle
What can increase the risk of getting heart diease?
- High level of saturated fat in the diet, which leads to a build up of cholesterol (a **plaque) **in the arteries
- High levels of salt, which can increase blood pressure
What can cause the coronary arteries narrow?
If there are plaques in the coronary arteries, it can reduce blood flow to the heart muscle.
What is thrombosis?
A blood clot
What are carbohydrates made of?
Simple sugars such as glucose
What is the function of carbohydrates?
Provide energy
Where are carbohydrates stored and in what form?
In the liver as glycogen or converted into fats
What are proteins made of?
Amino acids
What is the function of proteins?
Growth and repair of tissue
Provide energy in emergencies
Are proteins stored in the body?
No
What are fats made of?
Fatty acids and glycerol
What is the function of fats?
- Provide energy
- Energy store
- Provide insulation
Where are fats stored as and in what form?
Stored under the skin and around organs as adipose tissue
What is the function of vitamins and minerals?
Various functions
e.g. Vitamin C to prevent scruvy
What is the function of water?
To prevent dehydration
What is the difference between first and second class proteins?
First class proteins- (animal proteins) contain all the essential amino acids the body cannot make
Second class proteins- (plant proteins) do not contain these essential amino acids
How does balanced diet vary between people?
- Age- younger people need more proteins for growth, older people need more calcium for protection of bones
- Gender- females need more iron to replace iron lost through menstruation
- Physical activity- active people need more energy from food
What condition is caused by protein deficiency?
Kwashiorkor
Why do people in developing countries have poor diets?
- Overpopulation
- Lack of money to improve agriculture
How can EAR (Estimated Average daily Requirement) be measured?
EAR (g) = 0.6 x body mass (kg)
How can EAR be affected by pregnancy?
- Pregnant women need more protein to help their baby
- Breast feeding (lactating) needs extra protein to produce milk
What does BMI (Body Mass Index) measure?
Whether someone is underweight, overweight or obese
How can you calculate BMI?
BMI = body mass in kg / (height)² in m
Why is BMI not always reliable?
Muscle weighs more than fat
What are the 4 types of pathogens?
- fungi (e.g. athlete’s foot)
- bacteria (e.g. cholera)
- viruses (e.g. flu)
- protozoa (single-celled organisms e.g. dysentery)
What is **malaria **caused by?
A protozoan
What is the vector in malaria?
Mosquitoes are vectors, as they carry disease without getting it themselves
What is the parasite in malaria?
The protozoan is the parasite (Plasmodium), which feeds on the human red blood cells
What is a parasite?
An organism that feeds on/ lives off another living organism and often causes harm
What is the host in malaria?
Humans
How can you stop the spread of malaria?
- draining stagnant water
- putting oil on the water surface
- spraying insecticide
How can you reduce the risk of some cancers?
Changes in lifestyle and diet
How can you reduce lung cancer?
Not smoking
How can you reduce the risk of skin cancer?
Using sunscreen and less exposure to UV rays
What are **benign **tumours?
Divide slowly and are harmless, such as warts
What are **malignant **tumours?
Cells display uncontrolled growth and may spread (more dangerous)
What are pathogens?
Disease-causing organisms
What do pathogens cause?
Infectious disease by damaging the body’s cells
What do pathogens produce?
Poisonous waste producs called toxins
What do **antibodies **do?
Lock onto **antigens **on the surface of pathogens such as bacterium, killing the pathogen
What does the body produce to protect itself from pathogens?
White blood cells
How do phagocytes destroy pathogens?
- ingest and absorb the pathogens or toxins
- release an enzyme to destroy them
How do lymphocytes destroy pathogens?
- coat pathogens, clumping them together so that they are easily ingested by phagocytes
- release antibodies that stick to the antigen, stopping it from damaging the body
Do all pathogens have the same antigen?
No, each pathogen has its own antigens, so a specific antibody is needed for each pathogen
What is active immunity?
The white blood cells producing antibodies when a pathogen enters. When the body is infected again, the white blood cells can destroy the pathogen easily
What is passive immunity?
A vaccination for example, where the body is given antibodies from another human or animal
What is the process of vaccination?
- Injecting a live (harmless)/ dead/ weakened pathogen carrying antigens
- The antigens will trigger a response and the white blood cells produce correct antibodies
- **Memory cells **(a type of T-lymphocyte cell) remain in the body, providing long-lasting immunity
What do **antibiotics **and antiviral drugs do?
Antibiotics destroys pathogens and antiviral drugs slow down the pathogen’s development
What is the order in which drugs are tested?
- computer models
- human tissue
- animal
- human trials
What are the arguments for and against animal testing?
For
Against
Human benefits
An animal’s response could be different from human’s
Suffering can be minimised
Causes suffering to animals
What is a placebo?
A harmless pill
Why is a placebo used?
As a comparison in drug testing so the effect of a new drug can be assessed
Explain a blind trial during human testing
The *patient *does not know whether they are receiving a new drug or placebo
Explain a **double-blind trial **during human testing
Neither the *patient *nor the *doctor/nurse *know which treatment is being used
What does the double-blind trial prevent?
A biased opinion from the doctor/nurse or a ‘feel-good factor’ from the patient
What are the functions of the main parts of the eye?
- suspensory ligaments- alter the shape of the lens in focusing
- iris- controls amount of light entering eye
- pupil- allows light rays to enter the eye
- cornea- refracts light rays
- ciliary muscle- control suspensory ligaments
- lens- refracts and focuses light onto the retina
- retina- contains light receptors (rods and cones)
- optic nerve- carries nerve impulses to the brain
What is binocular and monocular vision?
- binocular- front of face, helps judge distance
- monocular- side of face, gives wider view
What is accomodation?
The ability of the lens to change its shape to focus near and distant objects
What happens when the eye focuses light from distant objects?
- ciliary muscles relax
- suspensory ligaments tighten
- lens is thin and less curved
What happens when the eye focuses light from near objects?
- ciliary muscles contract
- suspensory ligaments slacken
- lens is fat and more curved
What is the cause of colour blindness?
Lack of specialised cells in the retina
What does the eye look like when it is long-sighted?
- eyeball too short
- lens too thin
- image focused behind the retina
What does the eye look like when it is short-sighted?
- eyeball too long
- lens too rounded
- image focused in front of the retina
How can you correct long or short sightedness?
- corneal surgery
- glasses
- contact lenses
What lens can correct long-sightedness?
Convex
What lens can correct short-sightedness?
Concave
What are neurones?
Nerve cells
Where do nerve impuleses pass along?
The axon
List the reflex arc in order
- stimulus
- receptor
- sensory neurone
- central nervous system
- (relay neurone)
- motor neurone
- effector
- response
What is the pathway for a **spinal **reflex?
- receptor
- sensory neurone
- relay neurone
- motor neurone
- effector
How are neurones adapted?
- long
- branched endings (dendrites) to pick up impulses
- insulator sheath
What is the gap between neurones called?
synapse
How do synapses work?
- arrival of an impulse in pre-synaptic neurone
- vesicles containing neurotransmitters fuse with the presynaptic membrane releasing neurotransmitters into the synapse
- neurotransmitter diffuses across the synapse and binds to the receptor
- this generates an impulse in the post synaptic neurone
What do the classes of drugs represent?
- Class A- most dangerous and heaviest penalties
- Class B- mid dangerous and medium penalties
- Class C- least dangerous and lightest penalties
What are the types of drugs (with examples)?
- depressants (alcohol, solvents, temazepam)
- painkillers (aspirin, paracetamol)
- **stimulants **(nicotine, MDMA/ecstasy, caffeine)
- **performance enhancers **(anabolic steroids)
- hallucinogens (LSD)
How do depressants affect synapses?
- block the tranmission of nerve impulses across synapses
- binding with the receptor molecules in the membrane of the receiving neurone
How do stimulants affect synapses?
more neurotransmitter substances cross synapses
What is cilia?
Tiny hairs
Where are cilia found?
The epithelial lining of the trachea, bronchi and bronchioles
What is ‘smoker’s cough’ a result of?
- dust and particulates in cigarette smoke collecting and irritating the epithelial lining
- mucus not being moved by the cilia
What are the content of alcoholic drinks measured in?
Units of alcohol
What does drinking alcohol increase?
- reaction time
- risk of accidents
What is cirrhosis of the liver?
It is damaged when it breaks down toxic chemicals such as alcohol
What is homeostasis?
Keeping a constant internal environment involving balancing bodily inputs and outputs
What do automatic control systems do?
Keep the levels of temperature, water and carbon dioxide steady, making sure all cells can work at their optimum level.
What are negative feedback systems?
Cancel out a change such as decresing temperature level
Why is body temperature 37°C?
It is the **optimum temperature **for many enzymes
What can **high **temperatures cause?
- heat stroke
- dehydration
How does sweating cool the body?
- It increases heat transfer from body to environment
- **Evaporation **of sweat requires the body heat to change the liquid sweat in to water vapour
What is vasodilation?
The dilation of small blood vessels in the skin, causing more blood flow near the skin surface and resulting in more heat transfer
How does vasodilation work?
- body too hot
- small blood vessels in skin dilate
- blood flow increases
- more blood to surface
- lose heat
What can low temperatures cause?
- shivering
- hypothermia
What is vasoconstriction?
Constriction of small blood vessels in the skin, causes less blood flow and less heat transfer
How does vasoconstriction work?
- body too cold
- small blood vessels in skin constrict
- less blood flows through them
- reducing heat loss
Which area of the brain monitors blood temperature?
hypothalamus gland
Which area controls reaction to temperature extremes?
Nervous and hormonal systems, which trigger vasoconstriction or vasodilation
What hormone controls blood sugar levels?
Insulin
What is the difference between Type 1 and Type 2 diabetes?
- Caused by the pancreas not producing any insulin, so must be treated by injecting insulin
- Caused by either the body producing too little insulin or the body not reacting to it, can be controlled by changing diet and lifestyle
What does insulin do?
Convert excess glucose in the blood into glycogen
Where is glycogen stored?
The liver
What happens when blood glucose rises?
- detected by pancreas and releases insul into blood
- insulin travels in blood to liver
- liver takes in glucose and converts it to glycogen
- blood glucose falls to normal
What happens when blood glucose falls?
- detected by pancreas and stops producing insulin, produces glucogon
- glucogon travels in blood to liver
- liver converts glucogon back to glucose and releases to blood
- blood glucose increase to normal
What is phototropism?
The plant’s growth response to light
What is geotropism?
The plant’s growth response to gravity
How does a shoot’s growth respond?
- positively phototropic (grow towards light)
- negatively geotropic (grow away from the pull of gravity)
How does a root’s growth respond?
- negatively phototropic (grow away from light)
- positively geotropic (grow with the pull of gravity)
What are auxins?
A group of plant hormones which move trhough the plant in solution.
What are auxins involved in?
Phototropism and geotropism
Where are auxins made?
In the root and shoo tip
Where is more auxin usually found?
In the shady parts of the shoots
Why does this plant curve as it grows towards the light?
- more auxin is produced on the shady side
- this will increase the length of the cells
- therefore the shady side causes curvature of the shoot towards the light
What experiment could you use to test how auxins work?
- show auxins are produced in the tip of the plant (by covering certain areas of the shoot, bending is only prevented when the tip is covered)
- show auxins cause bending by building up on the shaded side of the root (by cutting the tip, placing on block of agar, block placed on one side of the shoot and the shoot bending away from auxin)
What are some uses of plant hormones?
- selective weedkillers
- rooting powder (increase root growth of cuttings)
- delay or accelerate fruit ripening
- control dormancy in seeds
What is dominant and recessive?
Dominant- the characteristic which is stronger and more likely to inherit
Recessive- the characteristic which is less likely to inherit and would need two recessive alleles to produce that characteristic
What are alleles?
Different versions of the same gene
What is a gene?
A section of DNA that codes for a particular characteristic
What is an allele?
Inherited characteristics are carried as pairs of alleles on pairs of chromosomes. Different forms of a gene are different alleles
What is meant by nature or nurture?
The affect of genetics and environmental factors over certain things such as intelligence, sporting ability and health.
What are chromosomes?
Thread-like structures in the cell nucleus that carry genetic information
How many chromosomes does a human have?
46 (23 pairs)
What do sex chromosomes determine?
The gender/sex of a mammal.
e.g. females have XX and males have XY
What sex chromosome does and egg and sperm have?
Eggs always carry X chromosomes and sperm carry either an X or Y chromosome
What is genetic variation caused by?
- mutations
- rearrangement of genes during the formation of gametes
- fertilisation which results in a zygote with alleles from the father and mother
What is a mutation?
Where the DNA within cells have been altered (this happens in cancer)
What is a monohybrid cross?
Only one pair of characteristics controlled by a single gene, one allele being dominant and one recessive
What is the difference between homozygous and heterozygous?
Homozygous means having identical alleles
Heterozygous means having different alleles
What is the difference between genotype and phenotype?
Genotype is their genetic make-up (e.g. Bb) and phenotype is the observable, physical characteristics of that organism (e.g. brown eyes)
What are inherited disorders caused by?
Faulty genes/alleles, most of which are recessive
What are the personal and ethical issues with genetic disorders?
- in deciding to have a gentic test (positive could alter their life)
- knowing the risk of passing on an inherited disorder (could change their decision to marry/ have a family)
Why is it difficult to predict the probability of inheriting disorders using genetic diagrams?
Because there is always a chance that the child may get both recessive alleles, even if it is 25%
