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Biology GCSE > B1 and B2 > Flashcards

B1 and B2 Flashcards

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1
Q

Eukaryotes

A

Eukaryotes are multicellular organisms made of eukaryotic cells

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2
Q

Eukaryotic cells

A

All have cell membrane, cytoplasm and genetic material enclosed in nucleus

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3
Q

Prokaryote

A

A single celled organism made of a prokaryotic cell

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4
Q

Nucleus

A

Contains genetic material that controls activities of the cell

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5
Q

Cytoplasm

A

Where most chemical reactions happen

Contains enzymes that control these reactions

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6
Q

Cell membrane

A

Holds cell together

Controls what goes in and out

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7
Q

Mitochondria

A

Where most reactions for aerobic respiration take place

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8
Q

Ribosomes

A

Where proteins made in cell

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9
Q

Cell wall

A

Made of cellulose, strengthens cell

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10
Q

Permanent vacuole

A

Contains cell sap, a weak solution of sugar and salts

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11
Q

Chloroplasts

A

Where photosynthesis occurs

Contain green substance - chlorophyll - absorbs light for photosynthesis

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12
Q

Bacteria cell

A

Cell membrane
Cell wall
Cytoplasm
No nucleus instead single circular strand of DNA floating freely
May contain 1 or more small rings of DNA - plasmids
No mitochondria

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13
Q

Light microscope

A 
Use light and lenses to let us see individual cells and large sub-cellular structures
Eyepiece 
Ocular lens (one in eyepiece)  
Coarse adjustment knob (bigger one)
Fine adjustment knob 
Objective lenses 
Stage 
Light
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14
Q

Electron microscope

A

Use electrons to form an image
Higher magnification and resolution than light
Let us see internal structure of mitochondria and chloroplasts and ribosomes and plasmids

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15
Q

Resolution

A

Ability to distinguish between two points

Gives sharper image

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16
Q

Image size

A

Real size times Magnification

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17
Q

How to prepare slide to view onion cells

A

1) Add drop of water to middle of clean slide
2) Cut onion and separate into layers. Use tweezers to peel of some epidermal tissue from bottom of layer
3) Place epidermal tissue into water
4) Add drop of iodine solution to stain
5) Place cover slip on top - make sure no air bubbles

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18
Q

Differentiation

A

Process by which a cell changes to become specialised for its job
In most animal cells they can no longer differentiate after becoming specialised
Lots of plant cells can always differentiate

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19
Q

Sperm cells

A

Long tail to help swim
Lots of mitochondria to provide energy
Enzymes in head to digest through egg cell membrane

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20
Q

Nerve cells

A

Longs cells to cover more distance

Branched connections at end

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21
Q

Muscle cells

A

Long cells so space to contract

Lots of mitochondria for energy needed to contract

22
Q

Root hair cells

A

Grow into long hairs that stick out into soil

Large surface area to volume ratio for absorbing mineral ions and water

23
Q

Phloem and Xylem cells

A

Cell are long and joined end to end
Xylem are hollow
Phloem few sub cellular structures
So easy transport of food and water

24
Q

Chromosomes

A

Coiled up lengths of DNA molecules
Body cells normally have two copies of each chromosome, 1 from mother and father
23 pairs of chromosomes in human cell

25
Q

Growth and DNA replication

A

In a cell that is not dividing DNA spread in long strings

1) Cell grows and increases amount of sub-cellular structures - mitochondria and ribosomes
2) Duplicates DNA to form X-shaped chromosomes
3) Mitosis

26
Q

Mitosis

A

1) Chromosomes line up at centre of cell and cell fibres pull them apart, 2 arms of each chromosome go to opposite ends of cell
2) Membranes form around each of the sets of chromosomes to become nuclei
3) Cytoplasm and cell membrane divide

27
Q

Binary fission

A

Prokaryotic cells replicate by binary fission

1) Circular DNA and plasmids replicate
2) cell gets bigger and circular DNA strands move to opposite poles
3) cytoplasm begins to divide and new cell walls begin to form
4) Cytoplasm divides and 2 daughter cells produced, each has 1 copy of circular DNA but has variable number of plasmids

28
Q

How to grow Bacteria in lab

A

Bacteria are cultured in a culture medium - contains carbohydrates, minerals, proteins and vitamins needed to grow
Culture medium can be a nutrient broth solution or solid agar jelly
Not kept above 25°C because harmful pathogens may grow

29
Q

How to spread bacteria on agar jelly

A

Petri dish and culture medium must be sterilised
Use inoculating loops but pass through flame to sterilise
Lid should be lightly taped to stop bacteria entering but oxygen must be able to enter
Store upside down to stop condensation falling on agar
Will form visible colonies on surface

30
Q

How to investigate effect of Antibiotics on binary fission

A

Leave small circles of paper soaked in antibiotic or antiseptic in agar
Do control just soaked in water
See how bacteria grows
Measure area of inhibition zone (where bacteria has not grown) after to see which is most effective

31
Q

Difference between Embryonic stem cells and Adult stem cells

A

Embryonic stem cells can differentiate into any cell in human body
Adult stem cells found in bone marrow can only differentiate into certain cells - blood cells

32
Q

Stem cells in plants

A

Stem cells found in meristems (where growth occurs)
Can differentiate into any type of plant cell
Can be used to make clones of plants

33
Q

Diffusion

A

Spreading out of particles from an area of higher concentration to lower concentration

Can occur in gases and solutions

34
Q

Diffusion in the cell membrane

A

Only small molecules can pass through the cell membrane - oxygen, glucose, amino acids, water
Big molecules can’t fit through - starch, proteins
The molecules move randomly but overall net movement from higher to lower concentration

35
Q

Osmosis

A

Movement of water molecules across a partially permeable membrane from a region of high water concentration to low concentration

36
Q

Practical to show osmosis

A

Experiment with potato chips and sugar solutions

37
Q

Method for osmosis practical

A

Cut potato into identical cylinders
Get beakers with different concentrations of sugar from pure water to 1mol/dm3
Measure mass of each potato cylinder
Put cylinder in each beaker and leave for 24 hours
Take out each cylinder and dry then take mass

38
Q

Results from osmosis practical

A

Calculate percentage in mass of each potato cylinder and plot on graph

39
Q

Variables for osmosis practical

A

Dependent - chip mass
Independent - concentration of sugar solution
Control - volume of solution, temperature, time, type of sugar

40
Q

Possible errors for osmosis practical

A

Potato cylinders not fully dried - mass increased
If water evaporates from beakers concentrations of solutions would change
Reduce errors by repeating experiment and calculating mean percentage change

41
Q

Active transport

A

Movement of substances against the concentration gradient

42
Q

Active transport in root hair cells

A

Concentration of minerals usually higher in root hair cell than in soil
Requires energy from respiration to absorb minerals

43
Q

Active transport in intestine

A

Higher concentration of nutrients in blood than in intestine
When higher concentration of glucose and amino acids in intestine they diffuse naturally
If not need active transport to allow nutrients to go into blood

44
Q

Surface area to volume ratios

A

Larger the organism the smaller surface area to volume ratio
Higher surface area to volume ratio means more exchanges can occur

45
Q

How are exchange surfaces adapted

A

Thin membrane - short distance to diffuse
Large surface area - more substances can diffuse at once
In animals - lots of blood vessels - get substances in and out of blood
Gas exchange surfaces often ventilated

46
Q

Gas exchange in lungs

A

Lungs need to transfer oxygen to blood and remove carbon dioxide

47
Q

Adaptations of alveoli

A

Large surface area
Moist lining so easier for gases to dissolve
Thin walls
Good bloody supply from capillaries

48
Q

Adaptations of villi

A

Increase surface area as protruding from small intestine
Single layer of surface cells
Network of capillaries

49
Q

How gases move in a leaf

A

Carbon dioxide diffuses into air spaces in leaf - then into cells where photosynthesis occurs
Oxygen and water vapour diffuse out of leaf through stomata
Water vapour evaporates from cells inside leaf
Then escapes by diffusion

50
Q

How leafs adapted for gas exchange

A

Flattened shape of leaf increases area of exchange surface
Underneath of leaf covered in stomata surrounded by guard cells to control loss of water
Air spaces inside leaf increase surface area of walls of cells to allow for more CO2 to enter

51
Q

What gases are exchanged in gills

A

Oxygen diffuses from water into blood

Carbon dioxide from blood to water

52
Q

Adaptation of gills

A

Each gills has lots of thin plates - gill filaments - large surface area
Gill filaments covered in lamellae - increase surface area
Lamellae - lots of capillaries, thin surface layer of cells
Blood flows through lamellae in one direction, water another - maintains high concentration gradient

Biology GCSE (5 decks)

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