AQA B1 chapter 1 Cell structure and transport

Question 1

what is resolution?

Answer 1

The ability to distinguish between two separate points in an image. A light microscope can resolve to point approx 200nm apart, but an electron microscope can resolve two points only 0.2nm apart.

Question 2

what structures are in animal cell?

Answer 2

cell membrane, ribosomes, mitochondria, cytoplasm and a nucleus

Question 3

what structures are in plant cell?

Answer 3

cell membrane, ribosomes, cellulose cell wall, mitochondria, cytoplasm, large permanent vacuole, chloroplasts and nucleus

Question 4

functions of the cell membrane

Answer 4

controls what enters and leaves the cell

Question 5

functions of the cytoplasm

Answer 5

jelly-like substance. Site of chemical reactions and contains enzymes

Question 6

functions of the nucleus

Answer 6

contains the genetic material (DNA)

Question 7

functions of ribosomes

Answer 7

site of protein synthesis

Question 8

functions of mitochondria

Answer 8

site of respiration

Question 9

functions of cellulose cell wall

Answer 9

strength and support to the plant. It is fully permeable.

Question 10

functions of chloroplasts

Answer 10

site of photosynthesis. Contains chlorophyll (green pigment) which traps light energy.

Question 11

functions of a large permanent vacuole

Answer 11

contains cell sap. Found in the cytoplasm.

Question 12

how do you set up a microscope?

Answer 12

start by clipping the slide you’ve prepared onto the stage
select the lowest-powered objective lens (i.e. the one that produces the lowest magnification).
use the coarse adjustment knob to move the stage up to just below the objective lens.
look down the eyepiece use the coarse adjustment knob to move the stage downwards until the image is roughly in focus
adjust the focus with the fine adjustment knob, until you get a clear image of what’s on the slide
if you need to see the slide with greater magnification, swap to a higher-powered objective lens and refocus.

Question 13

how to prepare a slide for a microscope

Answer 13

add a drop of water to middle of a clean slide
cut up an onion an separate it out into layers use tweezers to peel off some epidermal tissue from the bottom of one of the layers
using the tweezers, place the epidermal tissue into the water on the slide.
add a drop of iodine solution iodine solution is a stain stains are used to highlight objects in a cell by adding colour to them

Question 14

when calculating magnification what formula should we use?

Answer 14

magnification = image size divided by actual size of specimen

Question 15

for example an onion cell measures 5mm, it’s actual size is 0.05 micrometers. calculate its magnification

Answer 15

image size = 5 millimetres = 5000 micrometers
actual size of specimen = 0.5 micrometers
m = image size divided by actual size = 5000 divided by 5 = x1000

magnification = x1000

Question 16

how are sperm cells adapted for their function

Answer 16

St􏰀reamlined head and long t􏰀ail 􏰀to aid sw􏰈imming
􏰇 Man􏰁y mi􏰀tochondria 􏰃􏰈(where respira􏰀tion happens􏰆) 􏰈which s􏰅uppl􏰁y t􏰀he energy􏰁 􏰀to allow􏰈 t􏰀he cell 􏰀to move
􏰇 The acrosome (􏰃􏰀top of 􏰀the head)􏰆 has digestive en􏰉􏰁zymes 􏰈which break do􏰈wn t􏰀he o􏰅uter layers of membrane of the egg cell

Question 17

how are nerve cells adapted for their function

Answer 17

specialised to transmit electrical signals quickly from one place in the body to anot􏰀her 􏰇 The a􏰊xon is long􏰋 enabling 􏰀the imp􏰅ulses 􏰀to be carried along long dis􏰀tances
􏰇 Ha􏰄ving lo􏰀ts of e􏰊􏰀xtensions from t􏰀he cell body (called dendrites) means branched connections can form with other nerve cells
􏰇 The ner􏰄e endings hav􏰄e man􏰁y mi􏰀tochondria 􏰈which s􏰅uppl􏰁y 􏰀the energy􏰁 􏰀to make special 􏰀ransmi􏰀􏰀tter chemicals called neurotransmitters. These allow the impulse to be passed from one cell to another.

Question 18

how are muscle cells adapted to their function

Answer 18

special pro􏰀teins 􏰃(myosin and actin) slide over each other, causing the muscle to contract 􏰇 Lot􏰀s of mi􏰀tochondria 􏰀to prom􏰄ide energ􏰁y from respirat􏰀ion for con􏰀ract􏰀ion
􏰇 The􏰁y can s􏰀tore a chemical called gl􏰁ycogen 􏰀ha􏰀 is 􏰅sed in respirat􏰀ion b􏰁y mi􏰀tochondria􏰌

Question 19

how are root hair cells adapted to their function

Answer 19

Ha􏰄ve a large s􏰅urface area d􏰅ue 􏰀to root􏰀 hairs􏰋 meaning more 􏰈wa􏰀ter can mo􏰄ve in􏰌
􏰇 The large permanent􏰀 􏰄vac􏰅uole affec􏰀ts t􏰀he speed of mo􏰄vemen􏰀t of 􏰈wa􏰀ter from 􏰀the soil t􏰀o t􏰀he cell􏰌
􏰇 Mi􏰀tochondria t􏰀o prov􏰄ide energ􏰁y from respira􏰀tion for t􏰀he act􏰀iv􏰄e 􏰀transpor􏰀t of mineral ions int􏰀o t􏰀he
root hair cell.

Question 20

how are xylem cells adapted to their function

Answer 20

upon forma􏰀tion􏰋, a chemical called lignin is deposti􏰀ed 􏰈which ca􏰅uses t􏰀he cells t􏰀o die􏰌
They become hollow and are joined end-to-end to form a continuous tube so water and mineral ions can move through
􏰇 Lignin is deposi􏰀ted in spirals 􏰈which helps 􏰀the cells 􏰈wi􏰀ths􏰀tand 􏰀the press􏰅ure from 􏰀the mo􏰄vement􏰀 of water

Question 21

how are phloem cells adapted to their function

Answer 21

Cell 􏰈walls of each cell form s􏰀ructures called sieve plates when they break down, allowing the movement of substances from cell to cell
􏰇 Despit􏰀e losing many􏰁 su􏰅b-cellular structures, the energy these cells need to be alive is supplied by the mitochondria of the companion cells.

Question 22

what is a prokaryotic cell

Answer 22

prokaryotes are simple unicellular organisms e.g. a bacterium a cell without a nucleus

Question 23

what is a eukaryotic cell

Answer 23

Eukaryotic organisms are complex multicellular organisms e.g. a human, an oak tree.

Question 24

compare prokaryotic and eukaryotic cells

Answer 24

the size of prokaryotic cells are extremely small (less than 2 micrometers in diameter) whereas eukaryotic cells are much larger cells (10 micrometers-100 micrometers)
in a prokaryotic cell there is no nucleus on the other hand in a eukaryotic cell there is a nucleus present
in a prokaryotic cell DNA is circular (only one loop of DNA) whereas in a eukaryotic DNA is linear (many chromosomes)
prokaryotic cells have few organelles but eukaryotic cells have many organelles
an example of a prokaryotic cell is an ecoli bacterium and an example of a eukaryotic cell is a human skin cell.

Question 25

what is diffusion

Answer 25

diffusion is the net movement of particles from an area of high concentration to an area of low concentration diffusion is a passive process (no energy)

Question 26

how does potassium permanganate diffuse in warm water compared to cold water

Answer 26

Potassium permanganate has diffused quicker in the warmer beaker because the particles move quicker in hotter temperatures than they do in cold temperatures.

Question 27

what can affect diffusion

Answer 27

Temperature can affect the rate of diffusion if the temperature is hotter diffusion will happen at a quicker rate. If the diffusion distance is longer diffusion will take longer to spread out. Whereas if the diffusion is shorter it will be quicker. States of matter will affect how fast the particles move throughout the room. Gasses diffuse more quickly than liquids, solids do not diffuse at all.

Question 28

what is osmosis

Answer 28

the movement of water molecules from an area of high concentration to an area of low concentration across a partially permeable membrane.

Question 29

explain what would happen if bag made from semipermeable membrane is tied to a glass tube and filled with a concentrated sugar solution. This bag is placed in a less concentrated sugar solution.

Answer 29

The water molecules will move from a dilute solution (the water outside the bag) through the semipermeable membrane and moves into the concentrated solution (in the visking tube). The water then moves up the capillary tube because there is more than before. This process is called osmosis.

Question 30

describe and explain the process that takes place when a 30% sugar solution is then placed with an egg inside.

Answer 30

With the medium concentration water the egg has grown bigger there was 30% sugar. This is because the water has moved from a place of high concentration to a place a low concentration. The water has moved from the container into the semipermeable membrane. This is called osmosis. The water molecules will move from a dilute solution (the water outside the egg) through the semipermeable membrane and moves into the concentrated solution where the egg will have a lot of water inside it.

Question 31

what does it mean by lysic

Answer 31

lysic means burst

Question 32

what does it mean by crenation

Answer 32

crenation means shrivel

Question 33

describe what happens when cells are placed in distilled water compared to when they are placed in concentrated salt solution

Answer 33

when cells are placed in distilled water they swell and burst whereas when cells are placed in concentrated salt solution they shrink and shrivel

Question 34

describe and explain what happens when cells are placed in distilled water

Answer 34

the water moves from a dilute solution (inside the cell) to concentrate solution (outside the cell). The water moves through the partially-permeable into the cell and the cells swell and eventually burst (lysis).

Question 35

describe and explain what happens when cells are placed in a concentrated solution

Answer 35

the water moves from the concentrated solution (in the cell) through the partially-permeable-membrane to the dilute solution (outside the cell). The cells shrivel and shrink (crenation).

Question 36

how to investigate the effect of sugar or salt solutions on a plant tissue

Answer 36

Cut the potato into small pieces each different masses with a sharp knife. Prepare 6 different solutions each with a different amount of sugar inside. The 1st one will just be distilled water, 5% sugar, 10% sugar, 15% sugar, 20% sugar, 25% sugar and 30% sugar. Make sure to cut all the skin off. Cut them into 3cm for each potato piece. Weigh the potato pieces individually before they go in the water. Leave them in the water for at least 40 mins (the longer the better). After it has been in the water for at least 40 minutes take it out and measure it in grams (g) and record them individually. Record your results in the table on the next page

Question 37

conclusion describe and explain for investigating the effect of sugar or salt solutions on plant tissue.

Answer 37

With the 50% concentration water the potato has gone down in mass. This is because the water has moved from a place of low concentration (the potato) to a place of high concentration (the water). The water has moved from the potato through the semipermeable membrane. This is called osmosis. The water molecules have moved from a concentrated solution (the potato) through the semipermeable membrane and moves into the dilute solution where the boiling tube will have more water inside it than before. With the 0% the mass increased by 4%. This is because the water has moved from a dilute solution (the water) through the semi-permeable membrane into a now concentrated solution (the potato). With the 100% sugar the mass of the potato has decreased by 14.2%. This is because the water has moved out of the potato (the dilute solution) through a semi-permeable membrane into the beaker with the water (the concentrated solution) by a process of osmosis. At 0.3 mol/dm cubed there is no net movement in and out of the cell tissue, it was at equilibrium with the water.

Question 38

what is active transport

Answer 38

the movement of substances from an area of low concentration to an area of higher concentration. Against a concentration gradient, requires ATP energy and a carrier protein in the cell membrane.

Question 39

give two examples of active transport

Answer 39

E.g. glucose is sometimes actively transported from your small intestine into the bloodstream. E.g. mineral ions in water are actively transported from the soil into the root hair cells.

Question 40

how does a cell release energy

Answer 40

by respiration

Question 41

where in a cells does this happen

Answer 41

mitochondria

Question 42

what does more area mean in terms of active transport

Answer 42

The more area there is the more oxygen the more respiration which means energy is released which helps active transport happen more efficiently.

Question 43

how to work out surface area to volume ratio

Answer 43

find the surface area by adding up all of the faces's areas and find the volume by multiplying the width by the length by the height then simplify e.g. 24:8 would simplify to 3:1