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Biology > 2. Structure and functions in living organisms > Flashcards

2. Structure and functions in living organisms Flashcards

1
Q

What is the definition of an organelle?

A

Specialised cells with subcellular structures found within living cells

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2
Q

What is the definition of cells?

A

Basic structural unit of a living organism

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3
Q

What is the definition of a tissue?

A

Group of cells with similar structures, working together to perform the same function.

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4
Q

What is the definition of an organ?

A

Group of tissues , working together to perform specific functions.

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5
Q

What is the definition of an organ system?

A

Group of organs with similar functions, working together to perform body functions.

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6
Q

What is the nucleus function?

A
  • contains genetic material, which codes for particular protein
  • controls the cell
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7
Q

What is the cytoplasm function?

A
  • liquid substance in which chemical reactions occur
  • contains enzymes
  • organelles found in it
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8
Q

What is the cell membrane function?

A
  • contain receptor molecules to identify and selectively control what enters and leaves the cell
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9
Q

What is the mitochondria function?

A
  • where aerobic respiration reactions occur, providing energy for the cell
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10
Q

What is the ribosomes function?

A
  • where protein synthesis occurs
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11
Q

What is the function of chloroplasts?

A
  • where photosynthesis takes place, providing food for the plant
  • contains chlorophyll where photosynthesis occurs
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12
Q

What is the vacuole function?

A
  • contains cell sap
  • found within cytoplasm
  • improves cell’s rigidity
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13
Q

What is the cell wall function?

A
  • made from cellulose IN PLANTS
  • provides structure to the cell
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14
Q

What is a specialised cell?

A

Specialised cells are those which have developed certain characteristics in order to perform particular function.

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15
Q

What are the similarities and differences between a plant and animal cells?

A

Similarities:
- nucleus
- cytoplasm
- cell membrane
- mitochondria
- ribosomes

Differences (only in plants):
- chloroplasts
- permanent vacuole
- cell wall

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16
Q

Which chemical elements are present in carbohydrates?

A
  • carbon
  • oxygen
  • hydrogen

CHO

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17
Q

Which chemical elements are present in proteins?

A
  • carbon
  • oxygen
  • hydrogen
  • sulphur
  • nitrogen
  • phosphorus

CHONPS

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18
Q

Which chemical elements are present in lipids?

A
  • carbon
  • oxygen
  • hydrogen

CHO

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19
Q

Which molecules are carbohydrates broken down into?

A

The polymers break down into simple sugars

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20
Q

Which molecules are proteins broken down into?

A

The polymers break down into amino acids

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21
Q

Which molecules are lipids broken down into?

A

The large polymers break down into 3 fatty acids and glycerol

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22
Q

Practical: How to investigate food samples for the presence of glucose?

A
  1. Add BENEDICT’S SOLUTION into the test tube containing the food sample
  2. Heat in a water bath at 60-70 degrees for 5 minutes
  3. Take test tube out and record the colour
    –> if glucose is present the solution will turn brick red
    –> if glucose is not present solution will remain blue
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23
Q

Practical: How to investigate food samples for the presence of starch?

A
  1. Pipette the sample solution into wells or on a tile
  2. add drops of IODINE SOLUTION and leave for 1 minute
  3. record any colour change
    –> if starch is present the solution will turn blue-black
    –> is starch is not present the solution will remain brown
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24
Q

Practical: How to investigate food samples for the presence of protein?

A
  1. add the sample solution into a test tube
  2. add drops of BIURET SOLUTION into the test tube
  3. leave for 1 minute and then record the colour
    –> is protein is present the solution will turn purple
    –> if protein is not present the solution will remain blue
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25
Q

Practical: How to investigate food samples for the presence of fat (lipids)?

A
  1. add 2cm3 of ETHANOL to the test solution
  2. add 2cm3 of distilled water
  3. leave for 3 minutes and then record the colour
    –> if fat is present a milky white emulsion will form
    –> if fat is not present the solution will remain colourless
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26
Q

What is the role of enzymes?

A

Enzymes are biological catalysts
- protein molecules
- each has an active site where the substrate binds

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27
Q

Explain the effect of temperature during enzyme reactions?

A
  • optimum temperature is around 37 degrees
  • the rate of reaction increases with an increase in temperature up to this optimum, but above the optimum the rate of reaction decreases and eventually stops
  • when the temperature becomes too hot, the bonds in the structure break
  • this changes the shape of the active site, so the substrate can no longer fit
  • the enzymes begin to denature
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28
Q

Practical: Investigate how enzyme activity can be affected by changes in temperature

A
  1. Starch solution is heated
  2. Amylase is added
  3. Iodine is added to each well every minute
  4. Measure the time it takes for the iodine to stop turning blue-black (this means that starch is not present as amylase has broken the starch down into glucose
  5. Repeat test with different temperature
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29
Q

What is diffusion?

A
  • diffusion is the movement of particles from a high to low area of concentration
  • no energy is required
  • the molecules have to be small in order to move across
30
Q

How does the concentration gradient effect the rate of movement of substances?

A
  • the bigger the concentration gradient the faster the rate of movement
  • this is because more particles are randomly moving down the gradient than are moving against it
31
Q

How does the temperature effect the rate of movement of substances?

A
  • the greater the temperature, the greater the movement of particles
  • resulting in more collisions therefore a faster rate of movement
32
Q

How does the surface area effect the rate of movement of substances?

A
  • the greater the temperature, the more space for particle for move through
  • resulting in a faster rate of movement
33
Q

How does the distance effect the rate of movement of substances?

A
  • the further the particle shave to travel the longer it will take
34
Q

What is osmosis?

A
  • osmosis is the movement of water from a less concentrated solution to a more concentrated solution through a partially permeable membrane
  • does not require energy
35
Q

What is active transport?

A
  • active transport is the movement of particles from an area of lower concentration to an area of higher concentration i.e. against the concentration gradient
  • requires energy from respiration
36
Q

Practical: Investigate diffusion in non-living systems

A
  1. Cut 1cm3 cube of agar made of sodium hydroxide and phenolphthalein indicator
  2. Place cube in solution of hydrochloric acid
  3. Remove the the cube and wash with water to stop further reaction
  4. Cut the cube in half and measure the distance that the acid has caused agar to become colourless from outside inwards
  5. Repeat the experiment two more times and calculate the mean
  6. Repeat with different concentrations of hydrochloric acid
37
Q

Practical: Investigating osmosis in potatoes

A
  1. Place different sucrose solutions including 0% for a control, in different boiling tubes
  2. Put dry potato strips on a paper towel and measure the masses
  3. Place each potato strip into each sucrose solution for 20 minutes and record how the mass changed
  4. Repeat tests at each solution several times with potato strips of similar masses
38
Q

What is photosynthesis?

A

The process of making glucose from sunlight in the leaves of the plant.
Light energy is converted into chemical energy.

39
Q

What is the word equation for photosynthesis?

A

carbon dioxide + water –> glucose + oxygen

40
Q

What is the balanced chemical equation for photosynthesis?

A

6CO2 + 6H2O –> C6H12O6 + 6O2

41
Q

How does temperature affect photosynthesis?

A
  • an increase in temperature increases the rate of photosynthesis
  • however the reaction is controlled by enzymes, so follows the same trend
42
Q

How does light intensity affect photosynthesis?

A
  • for most plants the higher the light intensity the higher the rate of photosynthesis
  • as the distance between the light source and the plant increases the light intensity decreases
43
Q

How does the carbon dioxide concentration effect photosynthesis?

A
  • as the concentration of carbon dioxide increases the rate increases
  • carbon dioxide is also needed to make glucose
44
Q

Describe the structure of a leaf and how it is adapted for photosynthesis?

A

Waxy cuticle
- helps to reduce water loss via evaporation

Upper epidermis
- very thin and transparent in order to let light in to the palisade mesophyll

Palisade mesophyll
- contains lots of chloroplasts so that photosynthesis can happen rapidly

Spongy mesophyll
- have lots of air spaces to allow gases to diffuse in and out the cells faster
- it increases the surface area

Lower epidermis
- contains guard cells and stomata (gaps)

Guard cell
- kidney shaped cells that open and close the stomata by absorbing or losing water
- when lots of water is available, the cells fill and open stomata

Stomata
- where gas exchange and loss of water by evaporation takes place
- opens during the day closes at night

45
Q

Why do plants need magnesium?

A
  • chlorophyll production
  • causes leaves to turn yellow
46
Q

Why do plants need nitrate?

A
  • produce amino acids
  • causes stunted growth and turns leaves yellow
47
Q

Practical: investigating photosynthesis

A
  1. Use water plants, such as Elodea which releases bubbles of oxygen when photosynthesising
  2. Place a lamp with an LED bulb beside the beaker of water containing the water plant –> use LED to prevent raising the temperature
  3. Sodium hydrogen carbonate is added to the water to supple carbon dioxide
  4. This set up can be used to investigate the evolution of oxygen from a water plant
48
Q

Practical: investigating the effect of light intensity

A
  1. Place pondweed in water and set up a desk lamp next to a ruler so that you can measure the distance between the light and the beaker
  2. Move the lamp away by 10cm
  3. Leave for 5 minutes to allow for the pondweed to adapt
  4. Count the number of bubbles given off in 1 minute and record
  5. Repeat steps 2-4
49
Q

Practical: investigating the effect of carbon dioxide

A

Complete the same experiment as investigating the effect of light intensity but instead of testing the variable of light intensity by using a lamp, use different concentrations of sodium hydrogen carbonate solution.
Whilst keeping the other variables the same.

50
Q

Practical: investigating starch production

A
  1. Cover half of a small leaf with foil
  2. Place the plant on a windowsill for 48 hours so that light can reach it
  3. Put the leaf into boiling water to kill and preserve it
  4. Put the leaf in a boiling tube containing hot ethanol for 10 minutes (removes chlorophyll pigment)
  5. Dip the leaf in boiling water to soften
  6. Put leaf in a petri dish and cover with iodine solution
  7. The covered half of the leaf will remain orange brown, the exposed half will change to blue-black
51
Q

Practical: investigating whether photosynthesis requires chlorophyll

A

Repeat the starch production investigation but with a variated leaf. Variated leaves are white and green and only contain chlorophyll in the green areas.
Only the green parts will test positive for starch as a result of photosynthesis.
The white areas that do not contain chlorophyll with remain orange brown.

52
Q

What is the source and function of carbohydrates?

A

Source:
- bread
- pasta
- potatoes

Function:
- high energy source

53
Q

What is the source and function of proteins?

A

Source:
- meat
- fish
- eggs

Function:
- growth and repair

54
Q

What is the source and function of lipids?

A

Source:
- butter
- oil

Function:
- high energy source
- insulation

55
Q

What is the source and function of dietary fibre?

A

Source:
- vegetables
- bran

Function
- provide roughage to keep food moving through gut

56
Q

What is the source and function of vitamin A?

A

Source:
- carrots
- green vegetables

Function:
- needed for vision
- growth

57
Q

What is the source and function of vitamin C?

A

Source:
- citrus fruits
- broccoli
- peppers

Function:
- helps to absorb iron

58
Q

What is the source and function of vitamin D?

A

Source:
- margarine
- oily fish

Function
- helps to absorb calcium

59
Q

What is the source and function of calcium?

A

Source:
- milk

Function:
- bone and teeth strength

Can cause rickets

60
Q

What is the source and function of iron?

A

Source:
- red meat

Function:
- needed for haemoglobin

Can cause anaemia

61
Q

What is the source and function of water?

A

Source:
- water
- juice

Function:
- needed for cell reactions to take place

62
Q

What are the factors affecting energy requirements?

A

Age:
- energy requirements increase when we approach adulthood
- energy needs of adults go down as they age

Activity levels:
- more active = more energy needed

Pregnancy:
- energy requirements will increase in order to support growth of foetus
- energy also needs to increase due to the extra mass of the baby

63
Q

What is the function of the mouth in the human alimentary canal?

A
  • mechanical digestion: teeth break up large food pieces into smaller pieces with larger surface area
  • chemical digestion: amylase breaks down starch into glucose
  • salivary glands produce saliva to lubricate the food bolus so it can be swallowed easily
64
Q

What is the function of the oesophagus in the human alimentary canal?

A
  • tube from the mouth to the stomach
  • food bolus moves down due to unidirectional wave-like contractions created by circular muscles and longitudinal muscles that create a squeezing action
65
Q

What is the function of the pancreas in the human alimentary canal?

A
  • produces carbohydrase, protease and lipase enzymes
  • secretes enzymes into the stomach and small intestine
66
Q

What is the function of the stomach in the human alimentary canal?

A
  • gastric juice is released from stomach lining when it detects food in the stomach
  • gastric juice is made of
    –>pepsin: enzyme breaking down proteins
    –> hydrochloric acid: makes stomach acidic in order for pepsin to work and to kill any ingested bacteria
  • peristalsis also occurs here
  • the digested food is now called chyme
67
Q

What is the function of the small intestine in the human alimentary canal?

A

duodenum:
- the first part of the small intestine
- carbohydrates, protease and lipase digest food here
- bile is released into the duodenum
–> bile is produced in the liver and stored in the gallbladder. It has has 2 roles:
1) it is alkaline to neutralise the hydrochloric acid which comes from the stomach. The enzymes in the small intestine have a higher optimum pH than those in the stomach.
2) it breaks down large drops of fat into smaller ones. The larger surface area allows lipase to chemically break down the lipid into glycerol and fatty acids faster
- peristalsis also occurs here

ileum:
- lined with villi to maximise absorption of digested soluble molecules into blood
- villi have a thin lining, a large network of capillaries and have a large surface area

68
Q

What is the function of the large intestine in the human alimentary canal?

A
  • water is absorbed here, to produce faeces
  • faeces is stored in the rectum and then removed through he anus
69
Q

How is food moved through the gut by peristalsis?

A

Food is moved through the digestive system by a process called peristalsis close peristalsis Wave-like muscular contractions in the smooth wall of the gut which move food through the alimentary canal.

70
Q

What is the role of digestive enzymes?

A

carbohydrates (starch):
- broken down by carbohydrates
- starch –> maltose by amylase
- maltose –> glucose by maltase

proteins:
- broken down by proteases in the stomach and small intestine
- proteins –> amino acids

lipids:
- broken down by lipases
- lipids –> glycerol + 3 fatty acids

71
Q
A

Biology (9 decks)

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