Key Concepts in Biology Flashcards

1
Q

Describe how sperm cells are adapted to their function. ( 4 points)

A
  • haploid nucleus (contains the genes- 23 chromosomes)
  • long tail & streamlined to aid swimming
  • top of head has digestive enzymes to help break down the outer membrane of the egg cell
  • lots of mitochondria to supply the energy to allow the sperm to move
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2
Q

Describe how egg cells are adapted to their function. (3 points)

A
  • surrounded by special cell membrane which can only accept one sperm cell
  • lots of mitochondria to provide energy for the developing embryo
  • large size and cytoplasm allow quick repeated division as the embryo grows
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3
Q

Describe how ciliated epithelial cells are adapted to their function. (1 point)

A
  • long hair like structures called cilia which trap bacteria on their sticky mucus surface and killed by stomach acid
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4
Q

Identify the common parts of bacteria. (6 points)

A
  • cytoplasm
  • cell membrane
  • cell wall
  • chromosomal DNA (circular)
  • plasmids
  • flagella
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5
Q

Describe the function of the cytoplasm

A

liquid substance where chemical reactions occur, contain enzymes and organelles are found in it

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6
Q

Describe the function of the cell membrane

A

controls what enters and leaves the cell

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7
Q

Describe the function of the cell wall

A

provides structure to the cell and is made from cellulose

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8
Q

Describe the function of the chromosomal DNA

A

have no nucleus, this floats in cytoplasm

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9
Q

Describe the function of the plasmids

A

small rings of DNA, code for extra genes

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10
Q

Describe the function of the flagella

A

long, thin tail that allows them to move

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11
Q

Describe why bacteria are classified as being prokaryotic.

A

small and lack membrane-bound nuclei

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12
Q

Definition of an enzyme

A

biological catalyst that speeds up the rate of reaction without being used up

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13
Q

Differences between prokaryotic and eukaryotic cells

A

prokaryotes don’t have
- a nucleus

prokaryotes have:

  • chromosomal DNA
  • flagellum
  • cell wall
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14
Q

Give examples of enzymes (3 points)

A
  • carbohydrases-> amylase breaks down into maltose
  • lipases
  • proteases-> pepsin
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15
Q

What do carbohydrases do?

A

convert carbohydrates into simple sugars

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16
Q

what do proteases do?

A

Convert proteins into amino acids

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17
Q

what do lipases do?

A

convert lipids (fats) into fatty acids and glycerol

18
Q

where is amylase found?

A

salivary glands, pancreas and small intestine

19
Q

where is pepsin found?

A

produced in the stomach

20
Q

where is lipase produce?

A

in the small intestine and pancreas

21
Q

Explain why catalysis by enzymes is important for life processes

A

to speed up reactions

22
Q

Describe how to test for starch in food.

A

iodine reaction -> orange to blue black

23
Q

Describe how to test for reducing sugars in food.

A

Benedicts solution-> blue to reddish brown

24
Q

State what enzyme specificity means

A

lock and key hypothesis

25
an enzyme's action is due to its...
active site.
26
Stages of the lock and key hypothesis
Substrate diffuses into the active site and binds to it – the substrate must be a specific shape to fit into the enzyme The substrate forms temporary bonds with the AA’s in the enzyme to produce an ENZYME – SUBSTRATE COMPLEX The reaction takes place and the bonds in the substrate are broken – in this case, the larger molecule has been broken down into smaller molecules. An ENZYME – PRODUCT COMPLEX has formed The products unbind from the active site and diffuses out The enzyme is ready to be used again
27
Definition of an enzyme
a biological catalyst
28
How do enzymes become denatured?
Temperature, pH
29
Describe the effect of substrate concentration on enzyme activity.
as substrate conc increases, rate of reaction increases to a saturation point
30
Describe the effect of pH on enzyme activity.
too high or to low will affect amino acid chains and denature the protein
31
What is diffusion
a form of passive transport- movement of high conc to low
32
What is osmosis
a form of passive transport- movement of high conc to low- only applies to water across a selectively permeable membrane
33
what is active transport
a form of transport that does require energy
34
Describe what effect a mutation could have on the action of an enzyme.
a mutation is a change in a gene sequence, which changed the amino acid sequence, changes the shape of the protein/active site, preventing binding
35
Explain the role of the active site of an enzyme.
specific shape, bind to substratem catalyse reactions, lock and key hypothesis
36
Explain why phenolphthalein turns colourless when lipase breaks down the lipids in milk.
fatty acids are formed when the lipids are broken down | by lipase,and fatty acids are acidic (so the pH decreases)
37
Explain why the activity of lipase changes above a temperature of 40°C.
an increase in temperature above 40 °C causes changes in the shape of the active site of the enzyme.therefore the enzyme becomes denatured and no longer functions
38
Explain why enzymes can only catalyse specific reactions.
the active sit of an enzyme has a specific shape because of the order of amino acids, the substrate must have a shape which is complementary to the active site
39
Describe what happens to the molecule produced by transcription before it is translated.
leaves the nucleus, through the nuclear membrane and attached to ribosome
40
Explain how the lock and key hypothesis models how enzymes work.
 (enzyme and substrate have) complementary shapes  substrate fits into enzyme / enzyme substrate complex formed  reference to active site  enzymes break (chemical) bonds / form chemical bonds / (causes) reaction to occur / make products  Idea of products leaving enzyme (so that enzyme can be used again)
41
Describe how named factors affect the rate of enzyme-catalysed reactions.
A description to include some of the following points Temperature  (temperature) too low – not enough energy to make reactions occur (fast enough)  reference to optimum temperature  optimum for most (humans) - 37oC  over 37oC changes enzyme shape / changes active site shape of enzyme  therefore rate of reaction decreases / stops  enzymes denatured (if temperature too high) pH  optimum pH – around 7.3 / 6 to 8 for most enzymes  specific optimum quoted eg pepsin – pH 2 to 3  pH either side of optimum – changes the shape of the enzyme / shape of the active site  therefore rate of reaction decreases / stops  enzymes denatured (if pH too high / too low) substrate / enzyme concentration  higher concentrations faster reactions  due to more collisions  until maximum rate reached / all enzymes being used