Structure And Functions In Living Organisms Flashcards
(126 cards)
1
Q
What are the levels of organisation in living organisms?
A
Cells → Tissues → Organs → Organ Systems → Organism
2
Q
What is a cell?
A
The basic structural and functional unit of all living organisms.
3
Q
What is a tissue?
A
A group of similar cells that work together to carry out a specific function.
4
Q
What is an organ?
A
A structure made from different tissues working together to perform a function.
5
Q
What is an organ system?
A
A group of organs working together to perform a body function.
6
Q
Name 5 structures found in both plant and animal cells.
A
Nucleus, cell membrane, cytoplasm, mitochondria, ribosomes
7
Q
Name 3 structures found only in plant cells.
A
Cell wall, chloroplasts, permanent vacuole
8
Q
What is the function of the nucleus?
A
Contains genetic material and controls cell activities.
9
Q
What is the function of the mitochondria?
A
Site of aerobic respiration; releases energy.
10
Q
What is the function of ribosomes?
A
Site of protein synthesis.
11
Q
What is the function of the chloroplast?
A
Contains chlorophyll for photosynthesis.
12
Q
What is the function of the cell wall?
A
Provides support and structure; made of cellulose in plants.
13
Q
What is the function of the vacuole in plant cells?
A
Stores cell sap (water, sugar, salts); helps keep the cell firm.
14
Q
Name the three main biological molecules.
A
Carbohydrates, proteins, lipids
15
Q
What are carbohydrates made from?
A
Simple sugars like glucose
16
Q
What are proteins made from?
A
Amino acids
17
Q
What are lipids made from?
A
Fatty acids and glycerol
18
Q
What is the test for starch?
A
Iodine solution turns from orange-brown to blue-black.
19
Q
What is the test for glucose (sugar)?
A
Benedict’s solution + heat = brick-red if glucose is present.
20
Q
What is the test for protein?
A
Biuret solution turns purple if protein is present.
21
Q
What is the test for lipids?
A
Ethanol test – white emulsion appears if lipids are present.
22
Q
What is diffusion?
A
Movement of particles from a high to low concentration.
23
Q
What is osmosis?
A
Movement of water across a partially permeable membrane from high to low water concentration.
24
Q
What is active transport?
A
Movement of substances against a concentration gradient using energy (ATP).
25
Name 3 factors that affect the rate of diffusion.
Temperature, surface area, concentration gradient
26
What is photosynthesis?
The process by which plants make glucose using carbon dioxide, water, and sunlight.
27
What is the word equation for photosynthesis?
Carbon dioxide + water → glucose + oxygen (in the presence of light and chlorophyll)
28
What are the conditions needed for photosynthesis?
Light, carbon dioxide, water, chlorophyll
29
How is a leaf adapted for photosynthesis?
Large surface area, thin, chloroplasts, veins, stomata for gas exchange
30
What is the test for starch in a leaf?
Boil the leaf, remove chlorophyll with ethanol, then add iodine – turns blue-black if starch is present.
31
Name the 7 main nutrients in a balanced diet.
Carbohydrates, protein, lipids, vitamins, minerals, water, fibre
32
What is the function of fibre?
Helps with digestion and prevents constipation.
33
What is the function of iron?
Needed to make haemoglobin for red blood cells.
34
What does Vitamin C prevent?
Scurvy
35
Name the parts of the human digestive system.
Mouth, oesophagus, stomach, small intestine, large intestine, rectum, anus
36
What is peristalsis?
Waves of muscle contractions that move food through the gut.
37
What enzyme breaks down starch and where?
Amylase in the mouth and small intestine.
38
What enzyme breaks down protein and where?
Protease in the stomach and small intestine.
39
What enzyme breaks down lipids and where?
Lipase in the small intestine.
40
What does bile do?
Neutralises stomach acid and emulsifies fats.
41
What is respiration?
The process of releasing energy from glucose.
42
What is the word equation for aerobic respiration?
Glucose + oxygen → carbon dioxide + water + energy
43
What is the word equation for anaerobic respiration in humans?
Glucose → lactic acid + energy
44
Where does aerobic respiration happen?
In the mitochondria.
45
What is oxygen debt?
The extra oxygen needed to break down lactic acid after anaerobic respiration.
46
What is the purpose of gas exchange?
To take in oxygen for respiration and remove carbon dioxide as a waste product.
47
What is the main site of gas exchange in humans?
The alveoli in the lungs.
48
How are alveoli adapted for gas exchange?
Large surface area, thin walls (one cell thick), moist, rich blood supply, short diffusion distance.
49
What happens to the intercostal muscles and diaphragm during inhalation?
Intercostal muscles contract, diaphragm flattens, chest volume increases, pressure drops, air enters.
50
What happens during exhalation?
Intercostal muscles relax, diaphragm domes up, chest volume decreases, pressure increases, air is pushed out.
51
How does smoking affect the lungs?
Damages alveoli, reduces surface area, causes diseases like bronchitis, emphysema, and lung cancer.
52
When do plants carry out gas exchange?
All the time – they take in O₂ and give out CO₂ during respiration, but during daylight, photosynthesis also occurs.
53
Through what structures do gases enter and exit the leaf?
Through the stomata (mainly on the underside of the leaf).
54
How do guard cells help gas exchange?
They open and close stomata to control gas exchange and water loss.
55
What is the function of red blood cells?
Transport oxygen using haemoglobin.
56
How are red blood cells adapted?
Biconcave shape, no nucleus, contain haemoglobin.
57
What are the three types of blood vessels?
Arteries, veins, capillaries.
58
What are arteries?
Carry blood away from the heart; thick walls, small lumen, high pressure.
59
What are veins?
Carry blood to the heart; thinner walls, large lumen, valves to prevent backflow.
60
What are capillaries?
Tiny vessels for exchange of substances; one cell thick.
61
Name the four chambers of the heart.
Right atrium, right ventricle, left atrium, left ventricle.
62
Which side of the heart pumps blood to the body?
Left side – it’s thicker and pumps oxygenated blood.
63
What is the function of white blood cells?
Defend against disease – by phagocytosis or antibody production.
64
What is the function of platelets?
Help blood clot at wounds.
65
What does xylem do?
Transports water and minerals from roots to leaves.
66
What does phloem do?
Transports sugars and amino acids in both directions (translocation).
67
What is transpiration?
Loss of water vapour from the leaves through stomata.
68
What factors increase transpiration rate?
Higher temperature, lower humidity, increased wind, more light.
69
What is excretion?
The removal of waste products of metabolism (like CO₂ and urea).
70
What do the lungs excrete?
Carbon dioxide (from respiration).
71
What does the kidney excrete?
Urea, excess water, and salts (as urine).
72
What is urea?
A waste product formed in the liver from the breakdown of excess amino acids.
73
What are the main parts of the urinary system?
Kidneys, ureters, bladder, urethra.
74
What are receptors?
Cells or organs that detect stimuli (e.g., eyes, ears, skin).
75
What are effectors?
Muscles or glands that respond to stimuli.
76
What is the central nervous system (CNS)?
Brain and spinal cord.
77
What is a reflex action?
A fast, automatic response to a stimulus to protect the body.
78
What is the correct order of a reflex arc?
Stimulus → receptor → sensory neurone → relay neurone → motor neurone → effector → response.
79
What is the function of synapses?
They are gaps between neurones where impulses are transmitted using neurotransmitters.
80
What is a hormone?
A chemical messenger secreted by glands, carried in blood to target organs.
81
Name 2 hormones and their functions.
Insulin – lowers blood glucose.
Adrenaline – prepares body for 'fight or flight'.
82
What is homeostasis?
Maintaining a constant internal environment.
83
How does the body respond to high temperature?
Sweating, vasodilation (blood vessels widen), hairs lie flat.
84
How does the body respond to cold temperature?
Shivering, vasoconstriction (blood vessels narrow), hairs stand up.
85
What is phototropism?
A plant’s growth response to light (e.g., shoots grow towards light).
86
What hormone controls phototropism?
Auxin – it stimulates growth on the shaded side of the shoot.
87
What is the purpose of gas exchange?
To take in oxygen for respiration and remove carbon dioxide as a waste product.
88
What is the main site of gas exchange in humans?
The alveoli in the lungs.
89
How are alveoli adapted for gas exchange?
Large surface area, thin walls (one cell thick), moist, rich blood supply, short diffusion distance.
90
What happens to the intercostal muscles and diaphragm during inhalation?
Intercostal muscles contract, diaphragm flattens, chest volume increases, pressure drops, air enters.
91
What happens during exhalation?
Intercostal muscles relax, diaphragm domes up, chest volume decreases, pressure increases, air is pushed out.
92
How does smoking affect the lungs?
Damages alveoli, reduces surface area, causes diseases like bronchitis, emphysema, and lung cancer.
93
When do plants carry out gas exchange?
All the time – they take in O₂ and give out CO₂ during respiration, but during daylight, photosynthesis also occurs.
94
Through what structures do gases enter and exit the leaf?
Through the stomata (mainly on the underside of the leaf).
95
How do guard cells help gas exchange?
They open and close stomata to control gas exchange and water loss.
96
What is the function of red blood cells?
Transport oxygen using haemoglobin.
97
How are red blood cells adapted?
Biconcave shape, no nucleus, contain haemoglobin.
98
What are the three types of blood vessels?
Arteries, veins, capillaries.
99
What are arteries?
Carry blood away from the heart; thick walls, small lumen, high pressure.
100
What are veins?
Carry blood to the heart; thinner walls, large lumen, valves to prevent backflow.
101
What are capillaries?
Tiny vessels for exchange of substances; one cell thick.
102
Name the four chambers of the heart.
Right atrium, right ventricle, left atrium, left ventricle.
103
Which side of the heart pumps blood to the body?
Left side – it’s thicker and pumps oxygenated blood.
104
What is the function of white blood cells?
Defend against disease – by phagocytosis or antibody production.
105
What is the function of platelets?
Help blood clot at wounds.
106
What does xylem do?
Transports water and minerals from roots to leaves.
107
What does phloem do?
Transports sugars and amino acids in both directions (translocation).
108
What is transpiration?
Loss of water vapour from the leaves through stomata.
109
What factors increase transpiration rate?
Higher temperature, lower humidity, increased wind, more light.
110
What is excretion?
The removal of waste products of metabolism (like CO₂ and urea).
111
What do the lungs excrete?
Carbon dioxide (from respiration).
112
What does the kidney excrete?
Urea, excess water, and salts (as urine).
113
What is urea?
A waste product formed in the liver from the breakdown of excess amino acids.
114
What are the main parts of the urinary system?
Kidneys, ureters, bladder, urethra.
115
What are receptors?
Cells or organs that detect stimuli (e.g., eyes, ears, skin).
116
What are effectors?
Muscles or glands that respond to stimuli.
117
What is the central nervous system (CNS)?
Brain and spinal cord.
118
What is a reflex action?
A fast, automatic response to a stimulus to protect the body.
119
What is the correct order of a reflex arc?
Stimulus → receptor → sensory neurone → relay neurone → motor neurone → effector → response.
120
What is the function of synapses?
They are gaps between neurones where impulses are transmitted using neurotransmitters.
121
What is a hormone?
A chemical messenger secreted by glands, carried in blood to target organs.
122
Name 2 hormones and their functions.
Insulin – lowers blood glucose.
Adrenaline – prepares body for 'fight or flight'.
123
What is homeostasis?
Maintaining a constant internal environment.
124
How does the body respond to high temperature?
Sweating, vasodilation (blood vessels widen), hairs lie flat.
125
How does the body respond to cold temperature?
Shivering, vasoconstriction (blood vessels narrow), hairs stand up.
126
What is phototropism?
A plant’s growth response to light (e.g., shoots grow towards light).
