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Biology: Paper 1 > SB1 > Flashcards

SB1 Flashcards

Key concepts

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1
Q

What is a prokaryotic cell

A

A cell that does not have a nucleus

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2
Q

What is a eukaryotic cell

A

A cell that contain a nucleus

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3
Q

Function of nucleus

A

Part of the cell containing all an organisms genetic material

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4
Q

Function of cytoplasm

A

Liquid substance where chemical reactions occur

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5
Q

Function of cell membrane

A

Controls which substances can enter or leave the cell

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6
Q

Function of mitochondria

A

Provides energy for the cell via aerobic respiration

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7
Q

Function of cell wall

A

Cellulose (In plants) that provides structure

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8
Q

Function of chloroplasts

A

Contains chorophyll which absorbes light for photosynthesis

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9
Q

Function of vacuole

A

Contains cell sap to improve the cells rigidity

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10
Q

Function of chromosomal DNA

A

Contains genetic information for bacteria

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11
Q

Function of plasmid DNA

A

Small rings of DNA that carry genes for replication

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12
Q

What are specialised cells

A

Cells that are adapted to carry out a particular function

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13
Q

How are sperm cells specialised

A
  • Flagellum allows them to swim
  • Acrosome in the head containing enzymes to digest the
    egg cell membrane
  • Large number of mitochondria in the mid section to
    release energy for movement
  • Contains haploid nucleus
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14
Q

How are egg cells specialised

A
  • Cell membrane changes to prevent further sperm entry
  • Lots of mitochondria to release energy for the developing embryo
  • Haploid nucleus
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15
Q

How are ciliated epithelium cells specialised

A
  • Surface contains cilia (microscopic hairs) to sweep substances e.g. mucus
  • Large number of mitochondria to release energy
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16
Q

What does resolution mean

A

The ability of a microscope to destinguish two points of a specimen

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17
Q

How are electron microscopes more detailed than light microscopes

A

use beams of electrons, rather than light,
- electron microscopes have a lower wavelegnth which gives them a higher resolution

to produce images. Meaning more can be seen on a microscope slide with greater clarity.

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18
Q

What are the negatives of electron microscopes

A

*Organisms can only be seen in black or white
*Organisms have to be dead

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19
Q

What is the equation for magnification

A

magnification = image size/actual size

20
Q

What is the equation for the magnification of a light microscope

A

eyepiece lens x objective lens

21
Q

What are the steps for using a light microscope

A
  1. Place slide on stage and look through eyepiece lens
  2. Turn focus wheel to obtain clear image
  3. Start with lowest objective lens magnification
  4. Increase magnification of objective lens and refocus
22
Q

How do you prepare a slide

A
  1. Take thin layers of cells from sample using tweezers and place on slide
  2. Add a small amount of iodine as a stain to make cells more visible
  3. Apply coverslip taking caution to avoid air bubbles
23
Q

What is an enzyme

A

A biological catalyst that speeds up a reaction without being used up

24
Q

What is the lock and key hypothesis

A

That the shape of the substrate is complimentary to the shape of active site and will bond to form enzyme-substrate complexes

25
Q

What is the active site of an enzyme

A

part of the enzyme where substrate molecules bind and a chemical reaction takes place

26
Q

How can enzymes be denatured

A
  1. Increase beyond optimal temperature
  2. Excessive decrease/increase in pH
27
Q

What does denatured mean

A

when the active site has changed shape and can no longer form enzyme-substrate complexes

28
Q

How does temperature affect enzyme activity

A

rate of reaction increases with an increased temperature once passing the optimum, bonds that hold the enzyme break, causing it to denature

29
Q

how does the pH affect enzyme activity

A

if pH is too high or low active site will change shape and therefore denature

30
Q

how does substrate concentration affect enzyme activity

A

as concentration increases the rate of enzyme substrate complexes formed increases however once at saturation point (ALL THE ACTIVE SITES ARE OCCUPIED) the activity will plateau

31
Q

Practical: how can we investigate the effect of pH on enzyme activity

A
  1. Place 2 drops of iodine solution into each spot of spotting tile
  2. Add 2cm³ amylase, 2cm³ starch and 1cm³ of buffer pH into test tube
  3. Place solution in water bath of 35 degrees
  4. Use pipette to put solution into spotting tile every 20 seconds (should turn blue-black)
  5. Repeat until the solution stays orange (shows starch has been broken up)
  6. Redo practical with a different pH buffer and compare times
32
Q

What is the equation for rate

A

Rate = change / time

33
Q

What are carbohydrases

A

Convert carbohydrates into simple sugars

34
Q

What are proteases

A

Convert proteins into amino acids

35
Q

What are lipases

A

Convert lipids (fats) into fatty acids and glycerol

36
Q

What is the test for Starch and how is it done

A

Iodine test: add iodine solution to food sample
if starch is present will turn blue-black if not will stay orange

37
Q

what is the test for reducing sugars and how is it done

A

Benedict’s Solution test:
*Add 2cm³ of sample solution and 2cm³ of blue Benedict solution to test tube
*Place in boiling water bath for five minutes *Presence of reducing sugars turns solution brick red

38
Q

what is the test for protein and how is it done

A

biuret test: 1cm³ of 40% potassium hydroxide and 1% copper sulphate to food sample
Shake and if protein present colour will go from blue to violet

39
Q

what is the test for lipids and how is it done

A

Emulsion test: 2cm³ ethanol to food sample and 2cm³ deionised water and shake
If lipids are present solutions will turn cloudy

40
Q

how can the energy containing food be measured using calometry

A
  1. Place tube of 50ml cold water
  2. Record start temperature
  3. Place test tube at 45° and hold burning food sample underneath
  4. When food burns up record final temperature
41
Q

What is the equation for energy transferred

A

Energy transferred = volume of water x 4.2 x temperature increase

42
Q

What is osmosis

A

The movement of water particles from a concentrated solution to a dilute solution across the selective permeable membrane

43
Q

What is diffusion

A

The movement of molecules from a high concentration to a low concentration

44
Q

What is active transport

A

The movement of molecules against a concentration gradient requiring energy

45
Q

Core practical: Investigate osmosis in potatoes

A
  1. Cut potatoes into small discs of equal size
  2. Blot discs to remove excess water
  3. Measure initial mass of disc
  4. Place disks in sucrose solutions of different concentrations
  5. Blot with tissue again and record new mass
  6. Compre end mass - start mass
46
Q

How do you calculate percentage change

A

(Change in mass ÷ initial mass) x100

Biology: Paper 1 (5 decks)

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