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biology > 2. structure and functions in living organisms > Flashcards

2. structure and functions in living organisms Flashcards

2.2 -> 2.4, 2.7 -> 2.12, 2.15 -> 2.32, 2.33B, 2.34 -> 2.39, 2.49, 2.50, 2.55B, 2.56B, 2.57B, 2.58B, 2.71, 2.72B, 2.74B, 2.75B, 2.77B, 2.79B

1
Q

fill in the blanks
cells are separated from their surrounding environment by ____ ________, within this, there is _________, within this in eukaryotic cells the following organelles are present: _______, __________ (singular mitochondrion), _________
plant cells contain the following additional structures: ____ ____, _________, permanent _______

A

cell membrane
cytoplasm
nucleus
mitochondria
ribosomes
cell wall
chloroplasts
vacuole

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2
Q

describe the function of the nucleus

A

controls the cell, contains DNA

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3
Q

describe the function of the mitochondria

A

where aerobic respiration takes place, energy is released

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4
Q

describe the function of the ribosomes

A

site of protein synthesis

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5
Q

describe the function of cytoplasm

A

where cells chemical reactions takes place

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6
Q

describe the function of the cell membrane

A

controls what goes in and out of the cell

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7
Q

describe the function of the cell wall

A

made of cellulose (plants), supports the cell

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8
Q

describe the function of chloroplasts

A

contains a green pigment (chlorophyll), absorbs light for photosynthesis (making glucose)

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9
Q

describe the function of the vacuole

A

contains cell sap, help keeps the cells shape

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10
Q

the main structures in animal cells are:

A

nucleus, cell membrane, mitochondria, ribosomes, cytoplasm

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11
Q

in addition to the structures found in animal cells, what else do plant cells contain?

A

cell wall (made of cellulose), permanent vacuole (filled with cell sap, pushes the cytoplasm against the cell wall, keeping the cell turgid), and chloroplasts (site of photosynthesis)

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12
Q

what chemical elements are present in carbohydrates?

A

carbon, hydrogen, oxygen
(CHO)

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13
Q

what chemical elements are present in protein?

A

carbon, hydrogen, oxygen, nitrogen
(CHON)

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14
Q

what chemical elements are present in lipids (fats and oils)?

A

carbon, hydrogen, oxygen
(CHO)

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15
Q

how do carbohydrates get broken down?
-> name the molecule enzyme and product

A

starch -> amylase -> maltose -> maltase -> glucose

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16
Q

how do lipids get broken down?
-> name the molecule enzyme and product

A

large lipid droplets -> bile -> small lipid droplets -> lipase -> fatty acids and glycerol

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17
Q

how do proteins get broken down?
-> name the molecule enzyme and product

A

protein -> pepsin/ protease -> peptides -> trypsin (protease) -> amino acids

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18
Q

PRACTICAL
describe the test for reducing sugars:

A

-add benedicts solution to food sample
-place in 80C water bath for 5 mins
-colour change = blue -> brick red

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19
Q

PRACTICAL
describe the test for starch:

A

-add iodine solution to food sample
-colour change = orange -> blue black

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20
Q

PRACTICAL
describe the test for protein:

A

-add biuret solution to food sample
-colour change = blue -> purple

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21
Q

PRACTICAL
describe the test for lipids:

A

-emulsion test- add ethanol to food sample, shake
-add water, shake
-colour change = colourless -> cloudy white emulsion

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22
Q

what are some safety hazards for each food sample test?

A

-iodine is an irritant to the eyes, so wear goggles
-same with copper (II) sulfate in biuret solution
-ethanol is highly flammable, so keep away from Bunsen burner

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23
Q

definition of an enzyme

A

a biological catalyst that speeds up the rate of metabolic reactions without being changed or used up in the process

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24
Q

fill in the blanks: (mechanics of enzyme reaction)
the shape of the ________ is specific / ________ to the ______ ____

A

substrate
complementary
active site

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25
Q

describe the effect of temperature on enzymes:

A

-as temperature increases, so does the rate of metabolic reaction, as there is more kinetic energy and therefore more enzyme-substrate collisions occur
-the optimum temperature is 40C- this is when the most collisions happen
-too high temp= too much kinetic energy, active site changes shape, enzymes denature
-remember too low temp does not denature enzymes- instead, low rate of reaction due to the lack of kinetic energy

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26
Q

define diffusion

A

movement of molecules from a high to low concentration down a concentration gradient

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27
Q

define osmosis

A

net movement of water from a high water potential to a low water potential across a partially permeable membrane

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28
Q

define active transport

A

movement of molecules against a concentration gradient from a low to high concentration gradient. uses energy

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29
Q

where does diffusion occur?

A

in the lungs, alveoli, villi

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30
Q

where does osmosis occur?

A

large intestines, kidney

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31
Q

where does active transport occur?

A

root hair cells (have lots of mitochondria, so can respire, so have energy for active transport)

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32
Q

explain how the root hair cell takes up nitrate ions from the soil. what would happen if you added air?

A

by active transport- where the nitrate ions move from a low to high concentration against the concentration gradient, by using energy from respiration
by adding air, it increases oxygen, so increases respiration, so increases energy which is needed to complete active transport

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33
Q

fill in the blanks:
diffusion helps living organisms to:
-obtain many of their __________
-get rid of many of their _____ products
-carry out ___ exchange for __________

A

requirements
waste
gas, respiration

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34
Q

what would happen if an animal cell is placed in distilled water?

A

-cell has lower water potential than the solution
-so water moves into the cell via osmosis (high-low)
-cell will swell, may lyse (burst)

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35
Q

what would happen if an animal cell is placed in a strong sugar/salt solution?

A

-cell has higher water potential than solution
-so water moves out of the cell via osmosis (high-low)
-cell becomes crenated (shrivelled up)

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36
Q

what would happen if a plant cell is placed in a strong sugar/salt solution?

A

-cell has a higher water potential than the solution
-net movement of water out (loses water via osmosis (high-low))
-vacuole gets smaller and cell membrane shrivels away from cell wall
-becomes flaccid or plasmolysed

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37
Q

what would happen if a plant cell is placed in distilled water?

A

-cell has a lower water potential than the solution
-net movement of water in (gains water via osmosis (high-low))
-vacuole gets bigger, pushing the cell membrane against the cell wall
-becomes turgid

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38
Q

give one feature of the cell wall which allows the cell to become turgid

A

its elastic, strong and fully permeable

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39
Q

how does surface area affect the rate of diffusion?

A

greater the surface area to volume ratio is, the greater the rate of diffusion is

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40
Q

how does distance affect the rate of diffusion?

A

the smaller the distance, the faster rate of diffusion is (that’s why capillaries and alveoli have walls that are only 1 cell thick)

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41
Q

how does temperature affect the rate of diffusion?

A

the higher the temperature, the more kinetic energy there is, so the molecules are able to move/ spread faster- therefore increased diffusion rate

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42
Q

how does concentration gradient affect the rate of diffusion?

A

greater the difference in concentration, the faster the rate of diffusion is

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43
Q

what type of reaction is photosynthesis?

A

endothermic (chemical reaction that takes in energy from the surroundings- i.e. energy from sunlight is transferred to the chloroplasts)

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44
Q

describe the process of photosynthesis:

A

energy from sunlight is absorbed by chlorophyll
green plants use this energy to make the carbohydrate glucose from the raw materials carbon dioxide and water
at the same time, oxygen is made and released as a waste product

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45
Q

what is the word equation for photosynthesis?

A

carbon dioxide + water -> glucose + oxygen

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46
Q

what is the symbol equation for photosynthesis?

A

6CO2 + 6H2O -> C6H12O6 + 6O2

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47
Q

what are the limiting factors of photosynthesis?

A

temperature, light intensity, carbon dioxide concentration

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48
Q

how does temperature affect the rate of photosynthesis?

A

as temperature increases the number of collisions increases, therefore the rate of photosynthesis increases. however, at high temperatures, enzymes are denatured.

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49
Q

how does light intensity affect the rate of photosynthesis?

A

the more light a plant receives, the faster the rate of photosynthesis up to a certain point

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50
Q

how does co2 concentration affect the rate of photosynthesis?

A

the more co2 that is present, the faster the reaction occurs

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51
Q

what is the function of the waxy cuticle?

A

-reduces water loss by evaporation by waterproofing the leaves (protective layer on top)
-barrier to disease causing microorganisms
-contains few stomata- reduce water loss

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52
Q

what is the function of the upper epidermis?

A

thin and transparent- allows sunlight to reach the palisade mesophyll for photosynthesis

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53
Q

what is the function of the palisade mesophyll?

A

-column shaped, thin and arranged close together (uniformed)
-contains many chloroplasts and densely packed so that as much light energy can be absorbed as possible for efficient photosynthesis

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54
Q

what is the function of the vascular bundle?

A

-contains xylem and phloem to transport substances to and from the leaf
-xylem - transports water and mineral salts from the root to leaves (one way)
-phloem - transports sucrose and amino acids around the plant

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55
Q

what is the function of the spongy mesophyll?

A

contains internal air spaces that increases the surface area to volume ratio for the diffusion of gases (mainly co2)

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56
Q

what is the function of the lower epidermis?

A

-acts as a protective layer, contains more stomata compared to upper epidermis to regulate loss of water and site of gaseous exchange into and out of the cell (less exposed to light- so less evaporation of H2O)

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57
Q

what is the function of the stomata?

A

-regulates water loss (transpiration)
-site of gaseous exchange in the leaf

58
Q

what is the function of the guard cells?

A

controls the opening and closing of the stomata

59
Q

what are some adaptations of the leaf?

A
  • leaf = large SA - increases surface area for the diffusion of co2 and absorption of light for photosynthesis
  • thin - allows co2 to diffuse to palisade mesophyll quickly
60
Q

why do plants need mineral ions? which ones do they need most?

A

for growth
magneisum and nitrates

61
Q

how do plants obtain mineral ions?

A

actively absorbed from the soil by root hair cells

62
Q

why do plants need magnesium? what is its deficiency?

A

-to make chlorophyll (function)
-causes yellowing of the leaves (deficiency)

63
Q

why do plants need nitrates? what is its deficiency?

A

-to make amino acids (function)
-causes stunted growth and yellowing of the leaves (deficiency)

64
Q

what does a balanced diet consist of?

A

carbohydrates, proteins, lipids, dietary fibre, vitamins, minerals, water

65
Q

what are the sources and functions of carbohydrates?

A

function- source of energy
source- bread, cereals, pasta, rice, potatoes

66
Q

what are the sources and functions of protein?

A

function- growth and repair
source- meat, fish, eggs, pulses, nuts

67
Q

what are the sources and functions of lipids?

A

function- insulation and energy storage
sources- butter, oil, nuts

68
Q

what are the sources and functions of dietary fibre?

A

function- provides bulk (roughage) for the intestine to push food through
sources- vegetables, whole grains

69
Q

what are the sources and functions of water?

A

function- needed for chemical reactions to take place in cells
sources- water, juice, milk, fruits and vegetables

70
Q

what are the sources and functions of calcium?

A

function- needed for strong teeth and bones and involved in the clotting of blood
deficiency can lead to osteoporosis later in life
sources- milk, cheese, eggs

71
Q

what are the sources and functions of vitamin D?

A

function- helps the body to absorb calcium, and so required for strong teeth and bones
sources- oily fish, dairy products, also made naturally by the body in sunlight

72
Q

what are the sources and functions of vitamin C?

A

function- forms and essential part of collagen protein, which makes up skin, hair, gums and bones
deficiency can cause scurvy
sources- citrus fruit, strawberries, green vegetables

73
Q

what are the sources and functions of vitamin A?

A

function- needed to make the pigment in the retina for vision
sources- meat, liver, dairy, leafy green vegetables like spinach, eggs

74
Q

what are the sources and functions of iron?

A

function- needed to make haemoglobin (the pigment in red blood cells that transports oxygen)
sources- red meat, liver, leady green vegetables like spinach

75
Q

what affects energy requirements?

A

activity levels, age, pregnancy, sex

76
Q

how does age affect energy requirements?

A

energy young people need increases towards adulthood as this energy is needed for growth-so need a higher proportion of protein in their diet. energy needs of adults decreases as they age

77
Q

how does activity levels affect energy requirements?

A

the more active, the more energy required for movement as the muscles are contracting more and respiring faster

78
Q

how does pregnancy affect energy requirements?

A

increases as energy is needed to support the growth of the developing foetus, as well as the larger mass that the mother needs to carry around. extra calcium and iron are also needed in the diet to help build the bones, teeth and blood of the foetus

79
Q

how does breastfeeding affect energy requirements?

A

increases and extra calcium is still needed to make high quality breast milk

80
Q

how does sex affect energy requirements?

A

male average energy requirements tend to be more than females as they have a larger proportion of muscle mass

81
Q

how is food moved through the gut?

A

by peristalsis (which is muscle contraction)

82
Q

what is the alimentary canal?

A

channel/ passage where food flows through the body, starting at the mouth and ending at the anus (the digestive system)

83
Q

describe the structure and function of the mouth/ salivary glands

A

where mechanical digestion takes place- teeth chew food to break it down into smaller pieces and increase SA:V
amylase enzymes in saliva start digesting starch into maltose

84
Q

describe the structure and function of the oesophagus

A

tube that connects the mouth to the stomach
where peristalsis occurs (muscle contraction that pushes food down)

85
Q

describe the structure and function of the stomach

A

where food is mechanically digested by churning actions, while protease breaks down protein, hydrochloric acid is present to kill bacteria in food and provide the optimum pH for protease to work

86
Q

describe the structure and function of the small intestine

A

first section is called the duodenum which is where all food groups finish being digested
pH is slightly alkaline (around 8-9)
second section is the ileum which is where absorption of digested food molecules takes place into the blood (apart from water), it is long and lined with villi to increase SA

87
Q

describe the structure and function of the large intestine

A

water is absorbed, remaining material in the colon produces faeces which is stored in the rectum and removed through the anus

88
Q

describe the structure and function of the pancreas

A

makes enzymes for the small intestine (amylase, protease and lipase), secretes the enzymes in an alkaline fluid into the duodenum for digestion

89
Q

describe the structure and function of the liver

A

produces bile
amino acids that are not used to make proteins are broken down here (deamination) which produces urea

90
Q

describe the structure and function of the gall bladder

A

stored bile

91
Q

what is ingestion?

A

the taking in of substances, e.g. food and drink, into the body through the mouth

92
Q

what is mechanical digestion?

A

the breakdown of food into smaller pieces without chemical change to the food molecules- e.g. chewing, churning, emulsification- increases SA for enzymes to work on

93
Q

what is absorption?

A

the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells

94
Q

what is assimilation?

A

the movement of digested food molecules into the cells of the body were they are used, becoming part of the cells

95
Q

what is egestion?

A

the passing out of food that has not been digested of absorbed (as faeces) through the anus

96
Q

what is the purpose of digestion?

A

to break down large, insoluble molecules into smaller, soluble molecules that can be absorbed into the bloodstream

97
Q

what is the role of bile?

A

neutralising stomach acid
emulsifying lipids

98
Q

what are the adaptation of the villus in the small intestine?

A

-large surface area- lots of villi and microvilli
-short diffusion distance- walls are 1 cell thick
-high concentration gradient- lots of capillaries
-lacteal absorbs fat

99
Q

how is the small intestine adapted for absorption?

A

very long and has a highly folded surface with millions of villi (increases surface area)
peristalsis also occurs

100
Q

why do organisms need energy (ATP)?

A

-for muscle contraction (movement)
-maintain body temp
-metabolic reactions (making new molecules)

101
Q

compare aerobic and anaerobic respiration (oxygen, glucose breakdown, products, energy released)

A

AEROBIC
-oxygen needed
-glucose breakdown = complete
-products = CO2+H2O
-energy released = a lot

ANAEROBIC
-oxygen not needed
-glucose breakdown = incomplete
-products = animal cells- lactic acid, yeast- carbon dioxide and ethanol
-energy released = a little

102
Q

what is the word equation for aerobic respiration

A

glucose + oxygen -> carbon dioxide + water

103
Q

what is the symbol equation for aerobic respiration

A

C6H12O6 + 6O2 -> 6CO2 + 6H2O

104
Q

what is the word equation for anaerobic respiration in animals

A

glucose -> lactic acid

105
Q

what is the word equation for anaerobic respiration in plants and fungi

A

glucose -> ethanol + carbon dioxide

106
Q

what are the biological consequences to smoking? what chemicals cause this?

A

coronary heart disease
tar, nicotine, carbon monoxide

107
Q

how does tar affect the body due to smoking

A

tar is a carcinogen which is linked to increased chances of cancerous cells developing in lungs
contributes to COPD
causes chronic bronchitis (destroys cilia and mucus builds up which blocks bronchioles and leads to infections- smoker’s cough is the attempt to move this mucus)
causes emphysema (develops as a result of frequent infection, phagocytes break down alveoli so they become less elastic and cannot stretch, so burst, which reduces SA for gas exchange, which causes patients to become breathless and wheezy)

108
Q

how does nicotine affect the body due to smoking

A

narrows blood vessels leading to increased blood pressure, also increases heart rate- both of which can cause blood clots to form leading to heart attack or stroke
also is addictive

109
Q

how does carbon monoxide affect the body due to smoking

A

binds irreversibly to haemoglobin reducing the capacity of blood to carry oxygen
this puts more strain on the breathing system as breathing frequency and depth need to increase in order to get the same amount of oxygen in the blood, which increases risk of coronary heart disease and strokes

110
Q

how is water absorbed by root hair cells

A

via osmosis

111
Q

how are root hair cells adapted for efficient uptake of water (by osmosis) and mineral ions (a.t)

A

-large surface area for maximum water and mineral absorption
-lots of mitochondria, therefore lots of energy produced for active transport

112
Q

what is the route of water through a plant?

A

water moves by osmosis into the root hair cells (from high to low water potential) and into the xylem which is a hollow water tube made of cells and has walls strengthened by lignin, which transports the it to the mesophyll cells in the leaves

113
Q

what is transpiration

A

the evaporation of water from the leaves (stomata) of plants

114
Q

what is the function of transpiration

A

-transport mineral ions
-provides water to keep cells turgid
-provides water to leaf cells for photosynthesis
-keeps the leaves cool

115
Q

how does temperature affect transpiration?

A

increases
as high temp = more kinetic energy, therefore more molecules evaporate faster

116
Q

how does light intensity affect transpiration?

A

increases
as more sunlight = more photosynthesis, therefore more water used as a reactant and more stomata open, allowing water to be lost

117
Q

how does wind speed affect transpiration?

A

increases
as more wind = more water molecules moved away, which maintains the concentration gradient of water, so more water moves out by evaporation

118
Q

how does humidity affect transpiration?

A

decreases
high humidity reduces concentration gradient, so less water is lost

119
Q

what are the excretory products of the lungs

A

carbon dioxide and water

120
Q

what are the excretory products of the kidneys

A

water, mineral ions and urea

121
Q

what are the excretory products of skin

A

water and mineral ions

122
Q

what are the two functions of the kidney

A

-regulate water content of the blood (which is vital for maintaining blood pressure)
-excrete the toxic waste products of metabolism (such as urea and substances in excess of requirements such as salts)

123
Q

what is the nephron

A

-a tube in the kidney
-there are thousands/millions of them
-network of capillaries are wrapped all round it
-made up of several sections- bowmans capsule, proximal convoluted tubule, loop of henle, distal convoluted tubule, collecting duct

124
Q

what processes happen in the kidney (in order)

A
  1. ultrafiltration
  2. selective reabsorption of glucose
  3. reabsorption of water and salts
125
Q

describe what happens at the glomerulus

A

-capillaries get narrower as they get further into the glomerulus (which increases the pressure)
-this causes smaller molecules that are being carried in the blood to be forced out of the capillaries and into the bowman’s capsule (forms the filtrate)
-known as ultrafiltration
-small substances include glucose, water, urea, salts
-big substances that cant pass through include proteins, RBC, WBC and platelets

126
Q

where is water reabsorbed at in the kidney

A

loop of henle and collecting duct

127
Q

where are salts reabsorbed at in the kidney

A

loop of henle

128
Q

where is glucose reabsorbed at in the kidney

A

proximal convoluted tubul (PCT)

129
Q

where is urea reabsorbed at in the kidney

A

its not!

130
Q

what happens at the bowmans capsule

A

ultrafiltration

131
Q

describe what happens at the proximal convoluted tubule (PCT)

A

-selective reabsorption of glucose
-contains lots of mitochondria for active transport of glucose
-some water and salts also diffuse out via osmosis and A.T

132
Q

describe what happens at the loop of henle

A

-absorbs water
-is a salty environment (called the medulla) which helps water to move out of the nephron and back into the blood by osmosis
-salts are also reabsorbed by diffusion

133
Q

describe what the kidney would be like for someone with diabetes

A

-people with diabetes have high glucose levels in their blood, which means that not all the glucose filtered out can be reabsorbed, so ends up in the urine
-this is why one of the first tests a doctor may do to check if someone is diabetic is to test their urine for the presence of glucose

134
Q

what is the composition of urine

A

urea, mineral ions, water

135
Q

what would happen to your urine if you drink lots of fluids

A

the more fluids drunk, the more water will be removed from the body and so a large quantity of pale yellow, dilute urine will be produced

136
Q

what would happen to your urine in high temperature

A

the higher the temperature, the more water is lots in sweat and so less will appear in the urine, meaning a smaller quantity of dark yellow, concentrated urine will be produced

137
Q

PRACTICAL
describe the method of testing a leaf for starch

A

-boil leaf in water (with water bath or bunsen burner) to soften leaf and denature enzymes in plant cells
-boil leaf in ethanol (removes chlorophyll)
-drop iodine onto the leaf
-if turns blue black it contains starch-> therefore the area contains chloroplasts and has been photosynthesising

138
Q

PRACTICAL
plan an experiment investigating how light affects the rate of photosynthesis of elodea (pondweed)

A

c- light intensity
o- pondweed
r- 10x and find and average
m- rate of photosynthesis at varying distances e.g. 10,20,30,40,50,60,70,80,90,100cm
s-species of pondweed, no. of leaves in pondweed, length of pondweed, temperature

139
Q

PRACTICAL
how do you find out how much energy is in a certain food? (6marks)

A

-weigh banana chip
-use the same mass/ volume of water. measure temp
-light banana chip on fire
-heat water using banana chip
-burn until it has completely burnt
-measure change in water temp
-energy content = 4.2xmass of waterxtemp change/ mass of crisp
-repeat to make reliable

140
Q

what 3 measurements do you need to take before you burn the food when investigating the amount of energy in different foods practical

A

mass of food, starting temp of water, volume of water

141
Q

PRACTICAL
how do you use a potometer to estimate the rate of transpiration

A

-cut stem at slant underwater
-check for air leaks
-record where air bubble is starting from
-record after a certain amount of time where the air bubble finishes
-repeat the experiment and reset the air bubble

142
Q

how would you calculate the volume of water lost in the potometer practical (equation)

A

pi r squared x distance moved by air bubble

biology (6 decks)

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