Unit 1A - Human Biology

Question 1

What is needed for a balanced diet and why? (6)

Answer 1

Carbohydrates to release energy
Fats to keep warm and release energy
Protein for growth, cell repair and cell replacement
Fibre to keep everything moving smoothly through the digestive system
Vitamins and Minerals to keep skin, blood and bones healthy
Water

Question 2

Why do you need energy?

Answer 2

To fuel chemical reactions in your body
Reactions called metabolism
Speed they occur at is your metabolic rate

Question 3

What factors affect the amount of energy you need?

Answer 3

Muscle needs more energy than fat so people with a higher proportion of muscle have a higher metabolic rate
Bigger people need more energy
Men need more energy than woman
Genetics
Regular exercise means you have a higher metabolic rate

Question 4

What is malnourishment ?

Answer 4

When your diet is badly out of balance, fat or thin

Question 5

What leads to obesity?

Answer 5

Excess carbohydrates or fats

Question 6

What health problems arise from too much food?

Answer 6

Arthritis 
Type 2 diabetes 
High blood pressure
Heart disease
Cancer
Obesity

Question 7

Too much saturated fat or salt leads to what?

Answer 7

High blood cholesterol levels

High blood pressure and heart problems

Question 8

What does eating too little lead to?

Answer 8

Slow growth in children
Fatigue
Weak immunity system
Irregular periods in women

Question 9

What are deficiency diseases?

Answer 9

Lack of vitamins or minerals

Eg scurvy, lack of vitamin C

Question 10

What are the two main types of pathogen?

Answer 10

Bacteria

Viruses

Question 11

What are bacteria and what do they do?

Answer 11

Very small cells (micro organisms) that reproduce rapidly

They make you feel ill by damaging your cells and producing toxins

Question 12

What are viruses?

Answer 12

They are smaller than cells
They invade your cells and use them to reproduce
You feel ill when your cells burst releasing all the new viruses

Question 13

How does your body keep stuff getting into your body?

Answer 13

Skin
Hairs and mucus in respiratory tract
Platelets help blood clot fast to seal wounds to stop pathogens entering through cuts

Question 14

How does the immune system work?

Answer 14

White blood cells can engulf foreign cells and digest them
White blood cells produce proteins called antibodies that are specific to the pathogens antigen to kill it
Will reproduce rapidly if invaded again because of memory cells
Antitoxins produced to counteract toxins produced

Question 15

How does a vaccination work?

Answer 15

Inject small amounts of dead or inactive pathogens
White blood cells produce antibodies to counter the antitoxins
If live pathogens enter the body the antibodies can rapidly reproduce to counteract the antigens because of memory cells
Some vaccinations wear off over time so booster injections given to increase antibody levels

Question 16

What are the pros and cons of vaccinations?

Answer 16

Helped control many infectious diseases that were once common eg. MMR, smallpox no longer exists
Epidemics can be prevented as people who are vaccinated won’t get the disease and even those whose aren’t are less likely as there are less people to catch it from

Don’t always work
Sometimes bad side effects but very rare eg. Swelling, seizure or fever

Question 17

What do different types of drugs do to pathogens?

Answer 17

Painkillers relieve you from the symptoms but don’t kill the pathogen
Antibiotics actually kill or prevent the growth of bacteria specific antibiotics needed for specific bacteria
They don’t work on viruses because they develop inside your cells so difficult to kill them without killing the bodies cells

Question 18

How do bacteria become resistant to antibiotics?

Answer 18

Some can mutate to become resistant
This means when you use antibiotics they will survive
They will reproduce and the percentage of the population that are resistant increases due to natural selection
Resistant strain could lead to serious infection because of no cure
eg. MRSA
To slow down their development antibiotics shouldn’t be over prescribed and when are you need to finish the course completely

Question 19

How do you investigate the effectiveness of antibiotics on bacteria?

Answer 19

Bacteria are grown in a cultured medium (agar jelly) provides them with all the nutrients needed
Agar jelly is put in a Petrie dish and the bacteria is transferred onto it using inoculating loops
Paper discs soaked in antibiotics, non resistant bacteria die
All the equipment is sterilised prior to the experiment and a lid is placed on the Petri dish
At school 25 degrees used to stop harmful pathogens growing
In industrial conditions higher temperatures used to make them grow faster

Question 20

Who was Semmelweis?

Answer 20

Worked in Vienna general hospital in the 1840s
Saw a large number of women were dying after childbirth
Made doctors use antiseptic solution before entering his ward
Cut deaths from 12% to 2%
No one knew about bacteria at the time so couldn’t prove why it worked so the idea was dropped when he left the hospital increasing the number of deaths again

Question 21

What are the dangers of a new strain of bacteria or virus?

Answer 21

Could be antibiotic resistant
Could be a new strain that no one has encountered so no one is immune
This would lead to an epidemic as the new strain would spread rapidly

Viruses mutate often so hard to develop vaccines against them because their antigens are always changing
If the virus becomes very infectious and deadly this could lead to a pandemic

Question 22

What do sense organs detect?

Answer 22

Stimuli, a change in your environment

Question 23

What are the five sense organs, what receptors do they have and what are the stimuli they detect?

Answer 23

Eyes, light receptors, sensitive to light
Ears, sound and balance receptors, sensitive to sound and changes in position
Nose, smell receptors, sensitive to chemical stimuli
Tongue, taste receptors, sensitive to chemical stimuli
Skin, sensitive to touch, pressure, pain and temperature

Question 24

What is the CNS

Answer 24

The central nervous system
Where all the information from the sense organs is sent
Coordinates reflexes and actions
Consists of brain and spinal cord
Neurones used to transmit information
Instructions from CNS sent to the effectors (muscles or glands)

Question 25

What are the three type of neurones and what do they do?

Answer 25

Sensory neurones - carry electrical impulses from the receptors to the CNS Relay neurones - carry electrical impulses from the sensory to the motor neurones Motor neurones - carry electrical impulses from the CNS to the effectors

Question 26

What are effectors and what do they do?

Answer 26

Muscles - contract in response to an impulse | Glands - secrete hormones

Question 27

What is a synapse?

Answer 27

It is the connection between two neurones The impulse is transferred from one neurone to another by chemicals diffusing across the gap These set of a new impulse in the next neurone

Question 28

How do reflexes work and why are they important?

Answer 28

When a stimulus is detected by an effector an impulse is sent through a sensory neurone to the CNS It passes through the spinal cord or an unconscious part of the brain as this makes it faster as you don't think about it An impulse is sent through the relay neurone to the receptor causing the muscle to contract Because it is an unconscious movement it is fast which get you away from danger as fast as possible

Question 29

How are hormones transported around the body?

Answer 29

They are chemicals released directly into the blood so are transported by the blood plasma

Question 30

What do hormones do?

Answer 30

They affect specific cells called target cells | They control things in cells and organs that need constant adjustment

Question 31

What are hormones?

Answer 31

Hormones are chemical messengers which travel in the blood to activate target cells

Question 32

What are the differences between nerves and hormones?

Answer 32

``` Nervous responses are Fast actions Act for a very short time Act on a very precise area Hormonal responses are Slower actions Act for a longer time Act in a more general way ```

Question 33

What are the four stages of the menstrual cycle, when do they occur and what happens in each one?

Answer 33

Stage 1, Day 1-4, Lining of the uterus breaks down Stage 2, Day 5-14, Lining of the uterus build up Stage 3, Day 14, Ovulation Stage 4, Day 15-28, Lining of the uterus maintained

Question 34

What hormones are involved in the menstrual cycle, where are they produced and what do they do?

Answer 34

``` FSH Produced in the pituitary gland Causes egg to mature in ovaries Stimulates production of oestrogen Oestrogen Produced in ovaries Stimulates production of LH Inhibits production of FSH LH Produced by the pituitary gland Stimulates release of egg ```

Question 35

What hormones are used to prevent fertility and how do they work?

Answer 35

Oestrogen Increase levels constantly Inhibits production of LSH Egg never matures or develops Progesterone Stimulates production of thick cervical mucus which prevents any sperm reaching the egg

Question 36

What does the pill contain, how has it changed and why?

Answer 36

Progesterone and oestrogen First version made in 1950s had high levels of both hormones but found that oestrogen was linked to people getting blood clots Nowadays there are lower dosages of oestrogen

Question 37

What are the pros and cons of the pill?

Answer 37

It is over 99% effective at preventing pregnancy Reduces chances of getting some types of cancer There is still a small chance pregnancy could occur Can causes side effects such as headaches, nausea and irregular menstrual bleeding Doesn't protect against STIs

Question 38

How can hormones be used to increase fertility?

Answer 38

Some women have low FSH levels that prevent eggs from properly maturing which means they can't get pregnant FSH and LH can be injected in woman to stimulate egg maturity and release Doesn't always work though so could cost a lot having to do it a lot Also can cause too many eggs to be stimulated leading to unwanted multiple pregnancies (twins, triplets)

Question 39

What is IVF and how does it work?

Answer 39

In vitro fertilisation FSH and LH given to woman to stimulate egg production Eggs collected from woman's ovaries and fertilised using mans sperm in a lab Once the have developed into embryos they are checked for defects, one or two healthy ones are inserted into the woman's uterus

Question 40

What are the pros and cons of IVF?

Answer 40

Can give an infertile couple a child Some women have a strong reaction to the hormones eg. Abdominal pain, vomiting, dehydration. Reported increased risk of cancer Multiple births can happen if more than one embryo develops into a baby, increases chance of miscarriage and stillbirths

Question 41

What is auxin?

Answer 41

A plant growth hormone produced near the tips of shoots and roots Stimulates growth in shoots Inhibits growth in roots

Question 42

What happens if a tip of a shoot is removed?

Answer 42

The shoot may stop growing as no auxin is being produced as it is only produced in the tip

Question 43

Explain phototropism in shoots

Answer 43

Shoots are positively phototropic This means they grow towards light This is because auxin accumulates on the side away from the light Which means that that side grows at a faster rate (elongates) resulting in the shoot bending towards the light

Question 44

Explain geotropism in shoots and roots

Answer 44

Shoots are negatively geotropic meaning they grow away from gravity When a shoot grows sideways auxin accumulates on the lower side due to gravity This cause it to elongate resulting in the shoot bending away from gravity The same thing happens in roots but the auxin inhibits growth on the lower side causing the other side to elongate and for the root to bend towards gravity This means they are positively geotropic

Question 45

Explain hydrotropism in plants

Answer 45

Roots are positively hydro tropic This means they grow towards moisture If there is an uneven amount of moisture around the plant auxin will accumulate on the side with more moisture This inhibits growth on that side resulting in the other side elongating This means the root bends towards the water

Question 46

How are plant hormones used in agriculture?

Answer 46

Used in weed killers so that they only kill weeds which are broad leaved rather than the crops which have narrow leaves They only affect broad leaved plants Rooting powder used for cuttings contains auxin in it to help the plant grow

Question 47

What bodily levels need to be controlled in humans?

Answer 47

Ion content Water content Sugar content Temperature

Question 48

How is ion content regulated?

Answer 48

It is regulated by the kidneys They are taken into the body through food and absorbed into the blood Some is lost through sweat Kidneys remove excess ions from our blood by disposing of it through urine

Question 49

How are water levels maintained

Answer 49

``` It is taken in through food and drink It's lost: Through the skin as sweat Via the lungs in breath Via the kidneys as urine ```

Question 50

Explain the differences between urine concentration on a hot/exercising and cold/not exercising day

Answer 50

On a cold day/not exercising it will be more dilute as less water would have been lost through sweating This means there is more water lost through urine making it more dilute On a hot day/exercising it will be more concentrated as more water is lost through sweating and you will breathe more when exercising so more water is lost through your breath This means there will be less water lost through urine meaning it will be more concentrated

Question 51

What regulates body temperature?

Answer 51

The brain receives information from skin receptors so that it can maintain a temperature of 37 degrees as this is the best temperature for enzymes to work at

Question 52

How are blood sugar levels controlled?

Answer 52

Glucose enters out body through carbohydrates Metabolism of cells removes glucose from the blood for respiration Insulin is a hormone that is secreted to maintain the right level of glucose in the blood

Question 53

Why do people experience withdrawal symptoms?

Answer 53

Drugs are addictive because they change your body chemistry meaning that when you stop taking them physical symptoms occur

Question 54

What are the three types of drugs and give examples of each?

Answer 54

``` Medicinal - Antibiotics Recreational Legal - Alcohol Illegal - Cocaine Performance-Enhancing - Steroids ```

Question 55

What are the arguments for and against performance-enhancing drugs?

Answer 55

Athletes should have the right to make their own decision on whether to take drugs or not and if they're willing to take the health risks that come with them Drug free sport doesn't make it fair either way as people have better training facilities and coaches than others It's unfair if athletes benefit from drugs They may not be fully informed of the health risks that come with taking them

Question 56

What are statins?

Answer 56

Prescribed drugs used to lower the the risk of heart and circulatory disease Also lowers blood cholesterol

Question 57

What needs to happen before a new drug is released onto the market?

Answer 57

The new drug is first tested on human cells and tissue unless it drug that effects a whole or multiple body systems, if so then an animal is used It is then tested on a live animal to see if it works, if it is toxic and what is the best dosage Once it passes the animal testing it is tested on human volunteers in a clinical trial This is to see if there are any harmful side effects, low dosages are see to begin with and then slowly increased Then the drug is tested on people suffering from the illness to find the optimum dosage Then a double blind test is carried out on two groups of patients to test how well it works

Question 58

What is a double blind test?

Answer 58

This is where two groups of patients are given a drug, one group receives the actual drug the other receives a placebo Neither the patients or the doctor know which group received what This is so the results allow for the placebo effect and so the doctor is subconsciously biased towards the results

Question 59

What is an example of a drug going wrong when it wasn't tested properly?

Answer 59

Thalidomide, in the 1950s it was developed as a sleeping pill which it had been tested for People found it relieved morning sickness so pregnant woman started using it but it hadn't been tested on pregnant woman This resulted in their babies not developing limbs properly and being born disabled It is now used as a treatment for leprosy

Question 60

How is cannabis use linked to 'hard' drug use?

Answer 60

Seen as a stepping stone, people want to then try something stronger Gateway drug, people come into contact with drug dealers to obtain it which can lead to them being offered stronger drugs Genetics, some people are more likely to take drugs so if they take cannabis they'll take others too

Question 61

What are the impacts of tobacco and smoking?

Answer 61

Smoking causes disease in the heart, blood vessels and lungs The smoke also causes cancer Nicotine causes it to be addictive Alcohol affects the nervous system and slows down reactions Too much leads to impaired judgement, poor coordination and unconsciousness Excessive drinking can lead to brain damage and liver disease Alcohol is also addictive