Organisation Flashcards
(198 cards)
1
Q
What is a cell?
A
A cell is the basic unit of life in all living organisms.
2
Q
What are the main parts of an animal cell and their functions?
A
Nucleus – Contains genetic material and controls the cell’s activities.
Cytoplasm – Jelly-like substance where chemical reactions occur.
Cell membrane – Controls what enters and leaves the cell.
Mitochondria – Site of aerobic respiration, providing energy.
Ribosomes – Site of protein synthesis.
3
Q
What extra structures do plant cells have?
A
Cell wall – Provides strength and support.
Chloroplasts – Contain chlorophyll for photosynthesis.
Permanent vacuole – Contains cell sap to keep the cell rigid.
4
Q
How are living organisms organized?
A
Cells – Basic unit of life.
Tissues – Group of similar cells performing a function.
Organs – Made of tissues working together.
Organ systems – Group of organs performing a major function.
Organism – A complete living being
5
Q
Digestive System
A
Mouth – Mechanical digestion and enzyme action.
Stomach – Uses acid and enzymes to break down food.
Small intestine – Absorbs nutrients into the blood.
Large intestine – Absorbs water and forms waste.
Liver & Pancreas – Produce digestive enzymes.
6
Q
Circulatory System
A
Heart – Pumps blood.
Blood vessels – Arteries, veins, capillaries.
Blood – Transports oxygen, nutrients, and waste.
7
Q
Respiratory System
A
Lungs – Contain alveoli for gas exchange.
Trachea & Bronchi – Carry air to the lungs.
Diaphragm – Helps with breathing.
8
Q
Nervous System
A
Brain – Processes information.
Spinal cord – Sends signals between the brain and body.
Nerves – Transmit electrical impulses.
9
Q
Skeletal System
A
Bones – Provide structure and protection.
Joints & Muscles – Enable movement.
10
Q
What is cell specialization?
A
Cells develop different structures to perform specific functions (called differentiation)
11
Q
Examples of specialized cells:
A
Red blood cells – No nucleus, biconcave shape, carries oxygen.
Nerve cells – Long, with branched connections to send signals.
Muscle cells – Contain lots of mitochondria for energy.
Root hair cells (plants) – Large surface area for absorbing water.
Xylem & Phloem (plants) – Transport water and food.
12
Q
Why is cell specialization important?
A
It allows organisms to develop complex structures and systems for survival.
13
Q
What are stem cells?
A
Stem cells are undifferentiated cells that can develop into different cell types.
14
Q
Types of stem cells:
A
Embryonic stem cells – Can turn into any cell type.
Adult stem cells – Found in bone marrow, can become limited cell types.
Plant stem cells – Found in meristems, can grow into any plant cell.
15
Q
Uses of stem cells in medicine:
A
Treating diseases like diabetes and paralysis.
Growing new tissues for transplants.
Cloning plants for agriculture and conservation.
16
Q
Ethical issues of stem cells
A
Use of embryonic stem cells raises moral concerns.
Risk of rejection or mutations in treatments.
17
Q
What are enzymes?
A
Enzymes are biological catalysts that speed up chemical reactions in living organisms without being used up.
18
Q
What is the Lock and Key Model?
A
The enzyme has a specific active site that fits only one substrate. When the substrate binds, the enzyme speeds up the reaction, producing products.
19
Q
What factors affect enzyme activity?
A
Temperature – Too high = enzyme denatures; too low = reaction slows down.
pH – Too high or too low can denature the enzyme.
Substrate concentration – More substrate = faster reaction (until enzymes are fully occupied).
20
Q
Name three digestive enzymes and their functions.
A
Amylase (Salivary glands, pancreas, small intestine) → Breaks down starch into maltose (sugar).
Protease (e.g., Pepsin) (Stomach, pancreas, small intestine) → Breaks down proteins into amino acids.
Lipase (Pancreas, small intestine) → Breaks down lipids (fats) into glycerol & fatty acids.
21
Q
why do organisms need enzymes?
A
Digestion – Break down food into small, absorbable molecules.
Respiration – Release energy from glucose.
DNA Replication – Copy DNA before cell division.
22
Q
What are the three main factors that affect enzyme activity?
A
Temperature
pH
Substrate concentration
23
Q
How does temperature affect enzyme activity?
A
Low temperature – Slower reaction (molecules have less energy).
Optimum temperature (~37°C in humans) – Maximum enzyme activity.
Too high temperature – Enzyme denatures (active site changes shape, substrate no longer fits).
24
Q
How does pH affect enzyme activity?
A
Enzymes have an optimum pH where they work best.
Too acidic or too alkaline → Enzyme denatures (active site shape changes).
Example: Pepsin (stomach enzyme) works best in acidic conditions (pH ~2).
25
What happens to enzyme activity at different temperatures?
Low temperatures – Slow reaction due to less kinetic energy.
Optimum temperature – Fastest reaction rate (usually ~37°C in humans).
Too high temperature – Enzyme denatures (active site changes shape, stopping function).
26
What does it mean when an enzyme denatures?
The enzyme’s active site changes shape, so the substrate no longer fits.
This stops the enzyme from working.
Can be caused by high temperature or extreme pH.
27
What are the key factors that influence enzyme action?
Temperature
pH
Substrate concentration
Enzyme concentration
Presence of inhibitors
28
How Enzyme Concentration Affects Enzyme Action
More enzymes = faster reaction, as more active sites are available.
If substrate is limited, increasing enzyme concentration won’t increase the reaction rate.
29
What are enzyme inhibitors, and how do they affect enzyme action?
Competitive inhibitors – Bind to the active site, blocking the substrate.
Non-competitive inhibitors – Bind elsewhere on the enzyme, changing its shape so the substrate no longer fits.
Inhibitors slow down or stop enzyme activity.
30
What is a balanced diet?
A diet that provides the right amount of nutrients needed for health, in the correct proportions.
31
What are the seven main food groups needed for a balanced diet?
Carbohydrates
Proteins
Lipids (fats & oils)
Vitamins
Minerals
Fibre
Water
32
What is the function of carbohydrates?
Provide energy for the body.
33
What are good sources of carbohydrates?
Bread, pasta, rice, potatoes.
34
What is the function of proteins?
Used for growth and repair of body tissues.
35
What are good sources of protein?
Meat, fish, eggs, beans, nuts.
36
What are the functions of lipids?
Provide energy storage.
Insulation to keep the body warm.
Protect organs.
37
What are good sources of lipids?
Butter, oils, nuts, avocados.
38
Why are vitamins and minerals important?
Help with various body functions, such as maintaining healthy bones, skin, and the immune system.
39
Examples of vitamins and minerals?
vitamin C (found in citrus fruits) – Helps heal wounds.
Vitamin D (from sunlight, fish, eggs) – Needed for strong bones.
Iron (found in red meat, spinach) – Helps make red blood cells.
40
What is the role of fibre in the diet?
Helps with digestion by keeping the intestines healthy and preventing constipation.
41
What is the role of water?
Essential for all chemical reactions in the body.
Prevents dehydration.
42
Where can fibre and water be found?
Fibre – Whole grains, fruits, vegetables.
Water – Found in drinks and many foods like fruits.
43
What happens if a person has an unbalanced diet?
Too much food – Can lead to obesity, diabetes, and heart disease.
Too little food – Can cause malnutrition, weakness, and deficiency diseases.
44
Why do different people need different diets?
Diet depends on age, activity level, and health conditions.
Athletes need more protein and carbohydrates for energy.
Pregnant women need more nutrients for the baby’s growth.
45
What are biological molecules?
Large molecules essential for life, made from smaller subunits.
46
What are the four main types of biological molecules?
Carbohydrates
Proteins
Lipids (Fats and Oils)
Nucleic Acids (DNA & RNA)
47
What is the function of carbohydrates?
provide energy for the body.
48
What are carbohydrates made of?
Simple sugars (e.g., glucose).
49
Examples of carbohydrates?
Food sources?
Starch (plants)
Glycogen (animals)
Bread, pasta, rice, potatoes.
50
What is the function of proteins?
Used for growth and repair of body tissues and making enzymes.
51
What are proteins made of?
Amino acids joined in chains.
52
What are biological molecules?
Large molecules essential for life, made from smaller subunits.
53
What are the four main types of biological molecules?
Carbohydrates
Proteins
Lipids (Fats and Oils)
Nucleic Acids (DNA & RNA)
54
What are carbohydrates made of?
Simple sugars (e.g., glucose).
55
Examples of carbohydrates?
Starch (plants)
Glycogen (animals)
56
What is the function of proteins?
Used for growth and repair of body tissues and making enzymes.
57
What are proteins made of?
Amino acids joined in chains.
58
What are lipids made of?
Glycerol and fatty acids.
59
What is the function of lipids?
Energy storage
Insulation
Cell membranes
60
What is the function of nucleic acids?
Carry genetic information to control cell activities.
61
What are nucleic acids made of?
Nucleotides (sugar, phosphate, and a base).
62
Where are nucleic acids found?
In the nucleus of cells.
63
What are digestive enzymes?
Enzymes that break down large, insoluble food molecules into smaller, soluble molecules for absorption.
64
What does amylase do?
Breaks down starch into maltose (sugar).
65
Where is amylase produced?
Salivary glands
Pancreas
Small intestine
66
Where does amylase work?
Mouth & small intestine.
67
What does protease do?
Breaks down proteins into amino acids.
68
Where is protease produced?
stomach (as pepsin)
Pancreas
Small intestine
69
Where does protease work?
Stomach & small intestine.
70
What pH does pepsin work best at?
pH 2 (acidic – stomach conditions).
71
What does lipase do?
Breaks down lipids (fats and oils) into glycerol and fatty acids.
72
Where is lipase produced?
Pancreas
Small intestine
73
Where does it work?
Small intestine.
74
What is bile, and what does it do?
Bile is a liquid made in the liver and stored in the gallbladder.
75
How does bile help digestion?
Neutralises stomach acid (provides the right pH for enzymes in the small intestine).
Emulsifies fats (breaks fats into smaller droplets, increasing surface area for lipase to work).
76
What is the function of the digestive system?
77
What is the test for starch?
Add iodine solution. If starch is present, the solution turns blue-black.
78
What is the test for reducing sugars (e.g., glucose)?
Add Benedict’s solution and heat in a water bath. A positive result turns brick-red (or green/yellow for lower amounts).
79
What is the test for protein?
Add Biuret solution. If protein is present, it turns purple.
80
What is the test for lipids (fats)?
Use the emulsion test – add ethanol, shake, then add water. If lipids are present, a milky white emulsion forms.
81
What safety precautions should be taken during food tests?
Wear safety goggles, handle hot water baths carefully, and avoid direct skin contact with chemicals.
82
What is a positive result for Benedict’s test?
A color change from blue to green, yellow, orange, or brick-red, depending on sugar concentration.
83
What reagent is used for the starch test?
Iodine solution.
84
What does a negative result look like for the Biuret test?
The solution remains blue (no color change).
85
What is the control variable in food tests?
The volume of reagents used, the temperature of the water bath, and the time left to react.
86
What is the purpose of food tests?
To identify the presence of starch, reducing sugars, proteins, and lipids in food samples.
87
: What is the main function of the lungs?
To facilitate gas exchange by transferring oxygen into the blood and removing carbon dioxide.
88
Where does gas exchange take place in the lungs?
In the alveoli (tiny air sacs in the lungs).
89
What gases are exchanged in the lungs?
Oxygen (O₂) moves into the blood, and carbon dioxide (CO₂) moves out of the blood into the alveoli.
90
How are alveoli adapted for gas exchange?
✅ Large surface area for diffusion
✅ Thin walls (one cell thick) for a short diffusion distance
✅ Rich blood supply to maintain a concentration gradient
✅ Moist lining to dissolve gases
91
What is the role of the diaphragm in breathing?
The diaphragm contracts and flattens during inhalation, increasing lung volume and drawing air in.
92
How does inhalation (breathing in) occur?
✅ Intercostal muscles contract
✅ Ribcage moves up and out
✅ Diaphragm contracts and flattens
✅ Lung volume increases, air pressure decreases, and air is drawn in
93
How does exhalation (breathing out) occur?
✅ Intercostal muscles relax
✅ Ribcage moves down and in
✅ Diaphragm relaxes and moves up
✅ Lung volume decreases, air pressure increases, and air is forced out
94
What is diffusion in gas exchange?
The movement of gases from an area of high concentration to an area of low concentration.
95
Why is a steep concentration gradient important in gas exchange?
It ensures that oxygen continuously moves into the blood and carbon dioxide moves out efficiently.
96
How does smoking affect gas exchange?
❌ Damages alveoli, reducing surface area
❌ Increases mucus, blocking airways
❌ Reduces oxygen uptake, leading to breathing problems
97
What type of circulatory system do humans have?
A double circulatory system, meaning blood passes through the heart twice per circuit (one to the lungs, one to the body).
98
What are the main components of the circulatory system?
✅ Heart (pumps blood)
✅ Blood vessels (arteries, veins, capillaries)
✅ Blood (carries oxygen, nutrients, and waste)
99
What are the four chambers of the heart?
Right atrium, right ventricle, left atrium, left ventricle.
100
Which side of the heart pumps oxygenated blood?
The left side pumps oxygenated blood to the body through the aorta.
101
Which side of the heart pumps deoxygenated blood?
he right side pumps deoxygenated blood to the lungs through the pulmonary artery.
102
: What is the role of the valves in the heart?
To prevent backflow of blood and ensure it flows in one direction.
103
What is the function of the coronary arteries?
They supply oxygenated blood to the heart muscle.
104
What is the function of the vena cava?
It carries deoxygenated blood from the body to the right atrium.
105
What is the function of the pulmonary vein?
It carries oxygenated blood from the lungs to the left atrium.
106
What is the function of the aorta?
It carries oxygenated blood from the left ventricle to the body.
107
What is the function of the pulmonary artery?
It carries deoxygenated blood from the right ventricle to the lungs.
108
What is the natural pacemaker of the heart?
The sinoatrial node (SAN), which sends electrical impulses to control heartbeats.
109
What is the difference between arteries and veins?
✅ Arteries carry oxygenated blood away from the heart (except the pulmonary artery).
✅ Veins carry deoxygenated blood to the heart (except the pulmonary vein).
110
How are capillaries adapted for exchange?
✅ One cell thick walls for a short diffusion distance
✅ Large surface area for exchange
✅ Close to cells for efficient diffusion
111
What is the role of red blood cells in circulation?
To carry oxygen around the body using haemoglobin.
112
What are the three main types of blood vessels?
Arteries, veins, and capillaries.
113
What is the function of arteries?
To carry oxygenated blood away from the heart at high pressure (except the pulmonary artery).
114
How are arteries adapted to their function?
✅ Thick, muscular walls to withstand high pressure
✅ Elastic fibres to allow stretching and recoiling
✅ Narrow lumen to maintain high pressure
115
What is the function of veins?
To carry deoxygenated blood to the heart at low pressure (except the pulmonary vein).
116
How are veins adapted to their function?
✅ Thin walls as pressure is lower
✅ Large lumen to help blood flow easily
✅ Valves to prevent backflow of blood
117
What is the function of capillaries?
To allow exchange of gases, nutrients, and waste between blood and body cells.
118
How are capillaries adapted for exchange?
✅ Walls are one cell thick for a short diffusion distance
✅ Permeable walls for easy diffusion
✅ Very narrow so they can reach all cells
119
Why do veins have valves but arteries do not?
Because blood in veins is at low pressure, so valves prevent backflow. Arteries have high pressure, so backflow is not a problem.
120
What is the difference in lumen size between arteries and veins?
✅ Arteries have a narrower lumen to maintain high pressure.
✅ Veins have a wider lumen to allow easier blood flow at low pressure.
121
What is the main role of the circulatory system?
To transport oxygen, nutrients, and waste around the body.
122
What are the four main components of blood?
Red blood cells, white blood cells, platelets, plasma.
123
What is the function of red blood cells?
To carry oxygen around the body using haemoglobin.
124
How are red blood cells adapted to their function?
✅ Biconcave shape → increases surface area for oxygen diffusion
✅ No nucleus → more room for haemoglobin
✅ Contain haemoglobin → binds to oxygen to form oxyhaemoglobin
✅ Small and flexible → can squeeze through capillaries
125
What is the function of white blood cells?
To fight infection by engulfing pathogens or producing antibodies.
126
What are the two main types of white blood cells?
✅ Phagocytes → engulf and digest pathogens (phagocytosis)
✅ Lymphocytes → produce antibodies to destroy pathogens
127
What is the function of platelets?
To help blood clot at a wound and prevent excessive bleeding.
128
What is the function of plasma?
Plasma is the liquid part of blood that transports:
✅ Carbon dioxide (to the lungs)
✅ Glucose & nutrients (from digestion to cells)
✅ Hormones
✅ Urea (to the kidneys)
✅ Antibodies & waste products
129
What is haemoglobin?
A protein in red blood cells that binds to oxygen to form oxyhaemoglobin.
130
What is oxyhaemoglobin?
The form of haemoglobin when it binds with oxygen in the lungs. It releases oxygen in body tissues.
131
Why is blood considered a tissue?
Because it is made up of different types of cells working together.
132
What is cardiovascular disease (CVD)?
A term for diseases affecting the heart and blood vessels, including coronary heart disease and stroke.
133
What is coronary heart disease (CHD)?
A condition where coronary arteries get blocked or narrowed by fatty deposits, reducing blood flow to the heart muscle.
134
What causes coronary arteries to narrow in CHD?
The buildup of fatty deposits (atheroma) and cholesterol, leading to atherosclerosis.
135
What are the risk factors for cardiovascular disease?
✅ Smoking → damages artery walls
✅ High blood pressure → puts strain on arteries
✅ High cholesterol → leads to fatty deposits
✅ Obesity → increases strain on heart
✅ Lack of exercise → poor circulation and weight gain
✅ Genetics → inherited risk factors
136
What are the symptoms of coronary heart disease?
❌ Chest pain (angina)
❌ Shortness of breath
❌ Heart attack (if arteries get completely blocked)
137
How can CHD be treated with stents?
Stents are small metal tubes inserted into arteries to keep them open, improving blood flow.
138
What are the advantages and disadvantages of stents?
✅ Keeps arteries open and reduces heart attack risk
✅ Quick recovery after procedure
❌ Risk of blood clots forming near the stent
❌ Surgery carries some risks (infection, complications)
139
How can statins help treat CHD?
Statins are drugs that lower cholesterol levels in the blood, slowing down fatty deposit formation.
140
What are the advantages and disadvantages of statins?
✅ Reduces risk of heart disease and strokes
✅ Increases levels of good cholesterol (HDL)
❌ Must be taken long-term
❌ Possible side effects (headaches, liver damage)
141
What is health?
Health is a state of physical and mental well-being, free from disease.
142
What is a disease?
A disease is a condition that disrupts normal body functions. It can be communicable or non-communicable.
143
: What is a communicable disease?
A disease that can be spread between individuals, caused by pathogens (e.g., viruses, bacteria, fungi, parasites).
✅ Examples: Flu, COVID-19, tuberculosis (TB), malaria
144
What is a non-communicable disease?
A disease that cannot spread between people, often caused by lifestyle, genetics, or environment.
✅ Examples: Cancer, heart disease, diabetes
145
Q: How can different types of disease interact?
✔ Weakened immune system from a disease makes you more likely to get infections.
✔ Viruses (e.g., HPV) can increase the risk of cancer.
✔ Physical health issues can lead to mental health problems (e.g., depression from chronic illness).
146
What are the main causes of ill health?
✅ Communicable diseases (caused by pathogens)
✅ Non-communicable diseases (e.g., heart disease)
✅ Diet & lifestyle choices (poor nutrition, smoking, lack of exercise)
✅ Stress & mental health issues
✅ Environmental factors (pollution, lack of clean water)
147
: What are risk factors?
hings that increase the chance of developing a disease.
Examples:
✔ Smoking → Lung disease & cancer
✔ Obesity → Type 2 diabetes
✔ Excess alcohol → Liver disease
✔ Poor diet → Heart disease
148
How do lifestyle factors affect non-communicable diseases?
✔ Smoking → damages arteries, leading to heart disease and lung cancer
✔ Poor diet → leads to obesity, high cholesterol, and diabetes
✔ Lack of exercise → increases risk of heart disease and obesity
✔ Excess alcohol → causes liver damage and mental health issues
149
What is a carcinogen?
A substance that causes cancer by mutating DNA (e.g., tobacco smoke, radiation).
150
How can we prevent disease?
✅ Vaccinations (prevent viral & bacterial infections)
✅ Good hygiene (washing hands, clean water)
✅ Healthy lifestyle (exercise, diet, no smoking)
✅ Screening & check-ups (early detection of diseases)
151
What is a risk factor?
A lifestyle, environmental, or genetic factor that increases the chance of developing a disease.
152
What are non-communicable diseases?
Diseases that cannot spread between people and are often long-term, like heart disease, cancer, and diabetes.
153
Name some lifestyle risk factors for non-communicable diseases.
✅ Smoking
✅ Poor diet (high fat, sugar, salt)
✅ Lack of exercise
✅ Excess alcohol consumption
154
Name some environmental risk factors for non-communicable diseases.
✅ Air pollution → Can cause lung diseases
✅ Radiation exposure → Increases cancer risk
✅ Lack of clean water or healthcare → Affects general health
155
How does smoking increase the risk of disease?
❌ Damages artery walls → Leads to heart disease
❌ Causes lung cancer → Due to carcinogens in tobacco
❌ Reduces oxygen in blood → Leads to breathing problems
156
How does obesity increase the risk of disease?
❌ Increases risk of type 2 diabetes (affects blood sugar control)
❌ Raises blood pressure & cholesterol, leading to heart disease
❌ Can contribute to some cancers
157
How does excess alcohol increase disease risk?
❌ Liver disease → Alcohol damages liver cells
❌ Brain damage → Affects brain function
❌ Increased risk of cancer (e.g., mouth, liver)
158
How does poor diet contribute to disease?
❌ Too much fat → Leads to obesity and heart disease
❌ Too much salt → Raises blood pressure
❌ Lack of nutrients → Can cause deficiencies like rickets or anaemia
159
How does high blood pressure increase disease risk?
It puts strain on the heart and increases the risk of strokes, heart attacks, and kidney disease.
160
How do genetic factors increase the risk of non-communicable diseases?
Some diseases (e.g., certain cancers, heart disease, diabetes) can run in families due to inherited genes.
161
Can one risk factor cause multiple diseases?
es! Example: Smoking increases the risk of lung cancer, heart disease, strokes, and breathing problems.
162
How can we reduce the risk of non-communicable diseases?
✅ Exercise regularly
✅ Eat a balanced diet
✅ Avoid smoking & excess alcohol
✅ Maintain a healthy weight
163
What is cancer?
Cancer is the uncontrolled growth and division of cells, leading to the formation of a tumor.
164
What are tumors?
A mass of abnormal cells that form when cells divide uncontrollably.
165
What are the two types of tumors?
✅ Benign tumors – Stay in one place, do not spread, not cancerous but can be dangerous.
✅ Malignant tumors – Spread to other parts of the body and invade tissues, cancerous.
166
How do malignant tumors spread?
Through the bloodstream or lymphatic system, allowing cancer cells to invade other tissues (metastasis).
167
What are the main risk factors for cancer?
✅ Smoking – Contains carcinogens that cause lung cancer
✅ Obesity – Linked to bowel, liver, and kidney cancer
✅ UV exposure – Increases risk of skin cancer
✅ Viral infections – Some viruses (e.g., HPV) can trigger cancer
✅ Genetics – Some cancers run in families due to inherited faulty genes
168
What is a carcinogen?
A substance that causes cancer by damaging DNA (e.g., tobacco smoke, radiation).
169
How does smoking cause cancer?
How does smoking cause cancer?
170
How does UV radiation cause skin cancer?
UV rays damage DNA in skin cells, leading to mutations that cause uncontrolled cell division.
171
What are some common types of cancer?
✔ Lung cancer – Linked to smoking
✔ Skin cancer – Caused by UV exposure
✔ Breast cancer – Genetic and hormonal factors
✔ Bowel cancer – Linked to diet and obesity
✔ Cervical cancer – Caused by HPV infection
172
How is cancer treated?
✅ Surgery – Removes tumors
✅ Radiotherapy – Uses high-energy radiation to kill cancer cells
✅ Chemotherapy – Uses drugs to kill cancer cells or stop them dividing
173
What are the advantages and disadvantages of cancer treatments?
✔ Surgery – Removes the tumor, but cancer may return
✔ Radiotherapy – Kills cancer cells, but can damage healthy cells
✔ Chemotherapy – Effective, but causes side effects like hair loss and nausea
174
How can people reduce their risk of cancer?
✅ Stop smoking – Reduces lung cancer risk
✅ Use sunscreen – Protects against UV radiation
✅ Eat a healthy diet – Reduces obesity-related cancer risks
✅ Get vaccinated – HPV vaccine prevents cervical cancer
✅ Have regular screenings – Helps detect cancer early
175
What is plant cell organisation?
Plants are made up of organs (e.g., roots, stems, leaves), which work together to form a plant organ system for transport, support, and photosynthesis.
176
What are the main plant tissues?
✅ Epidermal tissue – Covers the plant, reduces water loss
✅ Palisade mesophyll – Contains chloroplasts for photosynthesis
✅ Spongy mesophyll – Air spaces for gas exchange
✅ Xylem and phloem – Transport water, minerals, and sugars
✅ Meristem tissue – Found in growing tips, contains stem cells
177
What is the function of the epidermal tissue?
Forms a protective outer layer, often covered by a waxy cuticle to prevent water loss.
178
What is the function of the palisade mesophyll?
Contains many chloroplasts to absorb light for photosynthesis. Located near the top of the leaf for maximum sunlight absorption.
179
What is the function of the spongy mesophyll?
Has air spaces to allow gas exchange (oxygen & carbon dioxide diffuse through the leaf).
180
What are xylem vessels?
Tubes that transport water and minerals from the roots to the rest of the plant, using transpiration.
181
What is transpiration?
The movement of water through a plant, from the roots, up the xylem, and out of the leaves as water vapor.
182
What are phloem vessels?
Tubes that transport sugars (glucose) around the plant via translocation.
183
What is translocation?
The movement of sugars (produced in photosynthesis) from the leaves to other parts of the plant for growth and storage
184
What is the function of meristem tissue?
Found in the growing tips of roots and shoots, containing stem cells that allow the plant to grow.
185
What factors affect transpiration rate?
✅ Light intensity → More light = faster transpiration
✅ Temperature → Higher temp = faster transpiration
✅ Humidity → More humidity = slower transpiration
✅ Wind speed → More wind = faster transpiration
186
What is the role of the stomata in gas exchange?
Tiny pores on the leaf surface that allow CO₂ in and O₂ out. They also control water loss.
187
What controls the opening and closing of stomata?
Guard cells swell to open stomata and shrink to close them, regulating water loss and gas exchange.
188
What is transpiration?
The loss of water vapor from a plant's leaves, through the stomata, caused by evaporation and diffusion.
189
What is the function of transpiration?
✅ Moves water up the plant for photosynthesis
✅ Transports minerals from roots to leaves
✅ Helps cool the plant through evaporation
190
What are the factors that affect transpiration rate?
✅ Light intensity – More light = faster transpiration
✅ Temperature – Higher temp = faster evaporation
✅ Humidity – More humidity = slower transpiration
✅ Wind speed – More wind = faster transpiration
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What are xylem vessels?
Hollow tubes made of dead cells, strengthened with lignin, that transport water and minerals from roots to leaves.
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What is the transpiration stream?
The continuous movement of water from roots to leaves through the xylem, driven by evaporation at the leaf surface.
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What are stomata?
Tiny pores on leaves that allow gas exchange and water loss.
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What controls the opening and closing of stomata?
Guard cells swell to open stomata and shrink to close them, regulating water loss and gas exchange.
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What is translocation?
he movement of sugars (glucose) and other nutrients through the phloem, from the leaves to the rest of the plant.
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How does translocation work?
✅ Uses phloem vessels
✅ Sugars are transported from sources (leaves) to sinks (roots, growing areas)
✅ Can move in both directions
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How are phloem vessels adapted for translocation?
✔ Made of living cells
✔ Have sieve plates (tiny holes for sugar movement)
✔ Supported by companion cells with lots of mitochondria for energy
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What is the main difference between transpiration and translocation?
✅ Transpiration – Moves water & minerals UP the plant via xylem
✅ Translocation – Moves sugars in BOTH directions via phloem
