Organisation - biology Flashcards
1
Q
Cells
A
Basing building blocks that make up all living organisms
2
Q
Differentiation
A
The process by which cells become specialised for a job. Occurs during the development of multicellular organisms
3
Q
What do specialised cells form
A
Tissues which form organs which form organ systems
4
Q
Tissue
A
A group of similar cells that work together to carry out a particular function
5
Q
Tissues in mammals
A
-Muscle tissue which contracts to move whatever it’s attached to
- Glandular tissue which makes and secretes enzymes and hormones
- Epithelial tissue, which covers some parts of the body
6
Q
Organ
A
A group of different tissues that work together to perform a certain function
7
Q
What tissue is the stomach made up of and what do the tissues do
A
-Muscular tissue moves the stomach wall to churn the food
- Glandular tissue makes digestive juices to digest food
- Epithelial tissue covers the outside and inside of the stomach
8
Q
Organ system
A
Group of organs working together to perform a particular function
9
Q
How are organs used in the digestive system to break down and absorb food
A
- Glands produce digestive juices
- The stomach and small intestine digests food
- The liver produced bile
- The small intestine absorbs soluble food molecules
- The large intestine absorbs water from undirected food, leaving faeces
10
Q
What do enzymes reduce the need for
A
Reduce the need for high temperature
11
Q
Catalyst
A
Substance that increases the speed of a reaction without being changed or used up in the reaction
12
Q
What are enzymes made up of
A
They are all large proteins and all proteins are made up of chains of amino acids
13
Q
How do enzymes catalyse a reaction through the lock and key model
A
Every enzyme has an active side with a unique shape that fits onto the substance involved in the reaction. This is because for the enzyme to work the substance has to fit into its active site.
14
Q
Problem with lock and key model
A
It is simpler than how enzymes actually work. In reality the active site changes shape a little as the substrate binds to it to get a tighter fit.
15
Q
How does temperature affect enzymes
A
A higher temperature increases the rate at first but if it gets too hot some of the bonds holding the enzymes together break. This changes the shape of the active sight of the enzyme so the substrate won’t fit anymore. The enzyme is said to be denatured
16
Q
How does pH affect enzymes
A
If it’s too high or too low throw pH interferes with the bonds holding the enzyme together. This changes the shape of the active site and denatures the enzyme.
17
Q
What it’s the optimum pH of an enzyme
A
Often neutral pH 7 but not always
18
Q
Why has the stomach got a pH of 2
A
Pepsin, an enzyme used to break down proteins in the stomach , works best at pH 2 which means it is well suited to the acidic conditions their
19
Q
Practical to investigate the effect of pH on enzyme activity
A
Set up a Bunsen burner, heatproof mat, tripod and gauze.
Place a beaker of water on the gauze and adjust the flame to keep the water at about 35°C.
Now put a drop of iodine solution into each spot of a spotting tile.
Add 2 cm3 of amylase enzyme solution to a test tube.
Place 2 cm3 of starch solution into the same tube.
Finally add 1 cm3 of pH solution to the tube. This will keep the pH constant.
Mix the solution in the test tube and place it into the beaker of water on the Bunsen burner.
Use a pipette to remove a few drops of solution every 20 seconds from the test tube and put them into a different well of the spotting tile.
Repeat until the iodine solution stops turning black.
Record the time this takes.
Repeat with different pH solutions.
20
Q
How to calculate the rate of reaction
A
100 divided by time (units are in s to the power of minus one)
21
Q
What do digestive enzymes do
A
Break down big molecules - starch, proteins and fats
22
Q
Why are digestive enzymes used to break down starch, fats and proteins
A
They’re too big to pass through walls of the digestive system so they have to be broken down into smaller molecules. These smaller soluble molecules can pass easily through the walls of the digestive system allowing them to be absorbed into the bloodstream
23
Q
What enzyme breaks down starch and what is it broken into
A
Amylase converts starch into simple sugars
24
Q
Where is amylase made
A
Made in salivary glands the pancreas and the small intestine
25
What enzyme breaks down proteins and what is it broken down into
Protease converts proteins into amino acids
26
Where is protease made
The stomach
The pancreas
The small intestine
27
What enzyme breaks down lipids and into what
Lipase converts lipids into fatty acids and glycerol
28
What are products of digestion used for
To make new carbohydrates, proteins and lipids.
Some of the glucose that’s made is used in respiration
29
What does bile do
Neutralises stomach acid and emulsifies fats
30
Where is bile produced, stored and released
In the liver but stored in the gall bladder before it’s released into the small intestines
31
How does bile neutralise the stomach
The hydrochloride acid in the stomach makes the pH too acidic for enzymes in the small intestine to work properly. Bile is an alkaline so neutralises the acid and makes conditions alkaline. The enzymes in the small intestine work best in these alkaline conditions.
32
How does bile emulsify fats
Breaks the fat into tiny droplets which gives a much bigger surface area of fat for the enzyme lipase to work on which makes digestion faster.
33
Where are enzymes used in the digestive system produced
Glands and the gut lining
34
Journey of digestive system
Food enters the body in the mouth. Mechanical digestion occurs by the teeth which breaks it into small pieces. Amylase in the saliva is secreted into the mouth by the salivary glands to start breaking down starch from the food into maltose. It then is sent down the oesophagus to the stomach.The stomach churns and pummels the food and digests proteins with the pepsin. The hydrochloric acid in the stomach kills most of the bacteria in the food.
The food is then sent to the small intestine where bile and enzymes are released.Lots of digestive enzymes made in the pancreas are released into the small intestine. Food molecules are now much smaller so can be absorbed through specialised intestinal walls and into the bloodstream. Food passes through the large intestine where excess water is absorbed from the food. It is finally stored in the rectum as faeces and excreted from the body through the anus.
35
Test for sugars
- Prepare a food sample and transfer 5cm cubed to a test tube
- Prepare a water bath so that it's set to 75 degrees
- Add some Benedict's solution to the test tube using a pipette
- Place the test tube in the water bath and leave for 5 mins
36
Colour change for Benedict's solution if sugar is present
Blue to green, yellow or brick red depending on how much sugar is in the food
37
Test for starch
Make a food sample and transfer 5cm cubed into a test tube
- Add a few drops of iodine solution and gently shake the tube
38
Colour change for iodine solution if starch is present
Browny orange to blue-black
39
Test for proteins
Makes a food sample and transfer 5cm cubed to a test tube
Add 2cm cubed of biuret solution to sample and mix
40
Colour change for biuret solution if iodine is present
Blue to purple
41
Test for lipids
Prepare sample of food but don't filter
Transfer 5cm cubed into test tube
Use a pipette to add 3 drops of Sudan III stain solution
42
Colour change for Sudan III solution
The top layer will be bright red
43
What are lungs protected by
The ribcage and surrounded y pleural membrane
44
Journey of the air you breathe in
Goes through the trachea, splits into two tubes called bronchi, one going into each lung.
The bronchi split into progressively smaller tubes called bronchioles
The bronchioles finally end at small bags called alveoli where the gas exchange takes place
45
What blood passes next to the alveoli
Has just returned from the rest of the body so it contains lots of co2 and very little oxygen.
46
How does deoxygenated blood gain oxygen
Oxygen diffuses out of the alveolus into the blood. Carbon dioxide diffuses out of the blood into the alveolus to be breathed out
47
What happens when the blood reaches body cells
Oxygen is released from the red blood cells and diffuses into the body cells. At the same time carbon dioxide diffuses out of the body cells into the blood. It's then carried back to the lungs.
48
What does the double circulatory system do
The right ventricle pumps deoxygenated blood to the lungs to take in oxygen. The blood then returns to the heart.
The left ventricle pumps oxygenated blood around all the other organs of the body. The blood gives up its oxygen at the body cells and the deoxygenated blood returns to the heart to be pimped out to the lungs again.
49
What are the walls of the heart made up of
Mostly muscle tissue
50
Function of valves
Make sure that blood flows in the right direction - they prevent it flowing backwards
51
Journey of the blood in the body
right atrium
right ventricle
pulmonary arteries in the lungs
pulmonary veins
left atrium
left ventricle
aorta
52
Coronary arteries
Branch off the aorta and surround the heart, making sure that it gets all the oxygenated blood it needs.
53
Function of pacemaker
A group of cells that control your resting heart rate. They produce a small electrical impulse which spreads to the surrounding muscle cells, cauing them to contract
54
Where is the pacemaker
In the right atrium wall
55
When is an artificial pacemaker used
To control heartbeat if the natural pacemaker cells don't work properllly.
56
Function of arteries
Carry blood away from the heart
57
Function of capillaries
Involved in the exchange of materials at the tissues
58
Function of veins
These carry blood to the heart
59
How are the lungs adapted for gas exchange
-Contains millions and millions of alveoli surrounded by a network of capillaries - rich blood supply
60
How are arteries adapted for their function
The heart pumps the blood out at high pressure so the artery walls are strong and elastic
The walls are thick compared to the size of the lumen
They contain thick layers of muscle to make them strong and elastic fibres to allow them to stretch and spring back
61
How are capillaries adapted for their function
Really tiny as they carry blood really close to every cell in the body to exchange substances with them.
Have permeable walls so substances can diffuse in and out
They supply oxygen and food, ad take away waste like c02
Walls only one cell thick to increase the rate of diffusion
62
How are veins adapted for their function
Blood is at a lower pressure in the veins so the walls don't need to be as thick as artery walls
They have bigger lumen than arteries to help the blood flow despite low pressure
Have valves to help keep the blood flowing in the right direction
63
4 main things in the blood
- Red blood cells
- White blood cells
-Platelets
- Plasmids
64
Red blood cell's job
To carry oxygen from the lungs to all the cells in the body
65
How are red blood cells adapted for their function
- Shape is a biconcave disc giving it a large surface area for absorbing oxygen
- They don't have a nucleus which allows more room to carry oxygen
- Contain haemoglobin which binds to oxygen
66
How are white blood cells adapted for their function
- Some can change shape to engulf microorganisms in phagocytosis
- Produce antibodies to fight microorganisms as well as antitoxins to neutralise any toxins produced by microorganisms
- Do have a nucleus
67
Platelet function
Platelets help blood clot at a wound to stop all your blood pouring out and to stop microorganisms getting in
68
A lack of platelets can cause
Excessive bruising and bleeding
69
Plasma function
A liquid that carries:
red and white blood cells
platelets
nutrients (glucose, amino acids)
carbon dioxide
urea
hormones
proteins
antibodies and antitoxins
70
How do stents combat heart disease
Inserted inside arteries. They keep them open, making sure blood can pass through to the heart muscle.
71
What is coronary heart disease
When the coronary arteries that supply the blood to the heart muscle get blocked by layers of fatty material building up. This causes the arteries to become narrow so blood flow is restricted
72
Advantages of stents
- Lower the risk of a heart attack
- Effective for a long time
- Recovery time from the surgery is relatively quick
73
Disadvantages of stents
- Risk of complications during the operation
- Risk of patients developing blood clots near the stent
74
How do statins combat heart disease
Reduce cholesterol in your body which slows down the rate of fatty deposits forming
75
Cholesterol
An essential lipid that your body produces and needs to function properly, however too much cholesterol can cause fatty deposits to form inside arteries.
76
Advantages of statins
- Can reduce the risks of strokes, coronary heart disease and heart attacks
- Can increase the amount of beneficial types of cholesterol
77
Disadvantages of statins
Long term drug that must be taken regularly
Can sometimes have side affects
Effect isn't instant, it takes time for their effect to kick in
78
Artificial hearts
Mechanical device that pumps blood for a person whose own heart has failed
79
Advantages of artificial heart
- Less likely to be rejected by the bodies immune system because they are made from metals or plastics
- There is not as big of a waiting process as a donor heart
80
Disadvantages of artificial heart
- Surgery to fit an artificial heart could lead to bleeding and infection
- Artificial hearts don't work as well as natural ones - the electric motor could fail
- Blood doesn't flow through artificial hearts as smoothly which can cause blood clots and lead to strokes
- The patient has to take blood thinning tablets which can cause problems with bleeding if they're hurt
81
How can valves in the heart be damaged or weakened
- Heart attacks
- Infections
- Old age
82
Examples of damaged valves
- Can cause the valve tissue to stiffen so it won't open properly
- Valve may become leaky, allowing blood to flow in both directions rather than just forward. This means that blood doesn't circulate as effectively as normal
83
How can severe valve damage be treated
Replacement valves - biological valves can be taken from humans or other mammals / mechanical valves
84
What is artificial blood
It is a blood substitute which is used to replace the lost volume of blood. This may give the patient enough time to produce new blood cells.
85
Health
The state of physical or mental wellbeing
86
Communicable diseases
Can spread from person to person or between animals and people
87
Non communicable diseases
Cannot spread between people or between animals and people
88
Factors that affect your health
- Diet - need a balanced diet
- Stress
- Life situation - access to medicine, wealth
89
Risk factors
Things that are linked to an increase in the likelihood that a person will develop a certain disease during their lifetime
90
Risk factors of lung cancer/ lung disease/ cardiovascular disease
Smoking as it damages the walls of the arteries and the cells in the lining of the lungs
91
Risk factors of type 2 diabetes
Obesity as it makes the body less sensitive or resistant to insulin
92
Risk factor of liver disease or brain function
Drinking too much alcohol as it can damage the nerve cells in the brain, causing the brain to lose volume
93
Risk factor of cancer
Exposure to certain substances or radiation - carcinogens
94
What is cancer caused by
Uncontrolled cell growth and division
95
Benign tumour
An abnormal cell growth that is contained within one area and does not invade other areas of the body.
96
Malignant tumour
A cancerous cell growth that invades neighbouring tissues and can spread to different parts of the body in the blood.
97
Lifestyle risk factors for cancer
- Smoking
- Obesity
- UV exposure
- Viral infection
98
Organs in plants
Stem, roots and leaves
99
Examples of plant tissues and what they do
- Epidermal tissue - covers the whole plant
- Palisade mesophyll tissue - part of the leaf where most photosynthesis takes place
- Spongy mesophyll tissue - in the leaf containing big air spaces to allow gases to diffuse in and out of cells
- Xylem and phloem - transport water, mineral ions, food, around the plant
- Meristem tissue - found at the growing tips of shoots and roots and is able to differentiate into lots of different types of plant cell, allowing the plant to grow
100
How does the structure of the epidermal tissue relate to its function
Covered with a waxy cuticle, which helps to reduce water loss by evaporation
101
How does the structure of the upper epidermis relate to its function
Transparent so that light can pass through it to the palisade layer
102
How does the structure of the palisade layer relate to its function
Has lots of chloroplasts, they are near the top of the leaf so can get the most light
103
How does the structure of xylem and phloem relate to their function
Form a network of vascular bundle, which deliverfood, nutrients and ewater to the plant
104
How are tissues of leaves adapted for efficient gas exchange
The lower epidermis is full of little holes called stomata, which let co2 diffuse directly into the leaf.
The air spaces in the spongy mesophyll tissue increase the rat of diffusion of gases.
105
What controls the opening and closing of the stomata
Guard cells
106
What do phloem tubes transport
Transport food substances (mainly dissolved sugars) made in the leaves to the rest of the plant for immediate use of storage
Transport goes in both directions
107
Structure of phloem
Columns of elongated living cells with small pores in the end walls to allow cell sap to flow through
108
What is the transportation of food substances in a leaf called
Translocation
109
Structure of xylem
Made of dead cells joined end to end with no end walls between them and a hole down the middle. They are strengthened by lignin
110
What do xylem transport
They carry water and mineral ions from the roots to the stem and leaves
111
What is transpiration
The movement of water from the roots, through the xylem and out of the leaves
112
What is transpiration caused by
The evaporation and diffusion of water from a plant's surface
113
How does transpiration work
Because there's more water inside the plant than in the air outside, the water escapes from the leaves through the stomata by diffusion
114
4 things transpiration is affected by
- Light intensity
- Temperature
- Air flow
- Humidity
115
How does temperature affect transpiration rate
The warmer it is the faster transpiration happens. When its warm the water particles have more energy to evaporate and diffuse out of the stomata
116
How does light intensity affect transpiration rate
The brighter the light the greater the transpiration rate
Stomata begin to close as it gets darker, photosynthesis can't happen in the dark so they don't need to be open to let co2 in. When stomata are closed very little water can escape
117
How does air flow affect transpiration rate
The better the air flow around a leaf, the greater the transpiration rate. If there's good air flow the water vapour is swept away, maintaining a low concentration of water in the air outside the leaf. Diffusion then happens quickly from an area of high concentration to an area of low concentration
118
How does humidity affect transpiration rate
The drier the air around the leaf, the faster transpiration happens. If the air is humid there's a lot of water in it already so the concentration gradient between inside and outside the leaf is not very high.
119
How to estimate the rate of transpiration
A single air bubble is introduced into the capillary tubing.
The tap on the reservoir is opened to add water to push the air bubble back to zero on the scale.
A timer is started and a set time measured.
The distance the air bubble has travelled along the scale is recorded.
The experiment can be repeated with different environmental conditions.
The faster the bubble moves, the greater the rate of water uptake – and so the greater the rate of transpiration.
120
Why can transpiration not be measured directly
Transpiration cannot be measured directly as some of the water will be used in photosynthesis.
121
How can transpiration be measured
The rate of transpiration can be calculated by measuring the distance travelled by an air bubble in a capillary tube over a given time. The faster the bubble moves, the greater the rate of water uptake – and so the greater the assumed rate of transpiration.
122
How are guard cells adapted to open and close stomata
- When the plant has lots of water the guard cells fill with it and go plump and turgid. This makes the stomata open so gases can be exchanged by photosynthesis
- When the plant is short of water the guard cells lose water and become flaccid, making the stomata close. This helps stop too much water vapour escaping.
Thin outer walls and thickened inner walls make the opening and closing work
Guard cells are sensitive to light and close at night to save water without losing out on photosynthesis
123
Where is more stomata usually found and why
More stomata is usualy found om the underside of a leaf as the lower surface is shaded and cooler so less water is lost through the stomata than if they were on the upper surface.
