Cell Structure and Transport

Question 1

Features of a Light Microscope

Answer 1

• 17th Century
• Beam of light
• 2000x
• Cheap
• Little training
• Easy to move
• Colour
• Small
• Passes through air

Question 2

Features of an Electron Microscope

Answer 2

• 1930s
• Beam of electrons
• 2,000,000 x
• Expensive
• Need training
• Hard to store
• Black and white
• Big
• Passes through vacuum

Question 3

Examining plant cells under a light microscope practical

Answer 3

1) Rotate lenses so that low power is in line with stage
2) Focus coarse so stage is close to lense
3) Place slide in middle of sage where light passes through
4) Focus slide by adjusting coarse
5) Draw low power image of what you see
6) Don’t look directly into light to damage eyes, take care when handling slides and placing plant cell

Question 4

Obtaining cell onto slide practical

Answer 4

1) Put small drop of water on slide
2) Peel very thing layer of onion skin with scalpel and tweezers
3) Use forceps to transfer skin into water droplet
4) Make sure skin is flat with no air bubbles
5) Put iodine drop on it
6) Place slide on arms of stage

Question 5

cm -> mm -> µm -> nm

Answer 5

cm x10 mm x1000 µm x1000 nm

cm ÷10 mm ÷1000 µm ÷1000 nm

Question 6

Magnification

Answer 6

Degree to which an image is made

Question 7

Resolution

Answer 7

Smallest interval measurable between two points on an image

Question 8

Nucleus

Answer 8

Controls all activities in the cell

Contains DNA

Question 9

Cytoplasm

Answer 9

Where all chemical reactions take place

Holds everything together

Question 10

Cell Membrane

Answer 10

Controls what goes in and out of the cell

Question 11

Mitochondria

Answer 11

Releases energy

Aerobic respiration

Question 12

Ribosomes

Answer 12

Makes protein for growth

Question 13

Chloroplast

Answer 13

Contains chlorophyll for photosynthesis

Question 14

Permanent Vacuole

Answer 14

Filled with cell sap

Supports cell and keeps it rigid

Question 15

Cellulose Cell Wall

Answer 15

Strengthens cell

Question 16

What eukaryotic cell doesn’t contain a nucleus

Answer 16

Red blood cell

Question 17

Eukaryotic Cells

Answer 17

Animals
Plants
Fungi
Protista

Question 18

Prokaryotic

Answer 18

Bacteria

Question 19

Difference between eukaryotes and prokaryotes

Answer 19

• Prokaryotes are smaller
• Prokaryotes have no nucleus
• Prokaryotes contain plasmids

Question 20

How are nerve cells adapted?

Answer 20

Fatty Sheath = insulate axon
Long axon = carry impulses long way
Lots of mitochondria = energy

Question 21

How are muscle cells adapted?

Answer 21

Contain special proteins = making fibres contract
Mitochondria = energy for cells to contract and relax
Store glycogen = cellular respiration, energy for fibres to contract

Question 22

How are sperm cells adapted?

Answer 22

Long tails = travel long distances
Mitochondria = energy for tail to work
Digestive enzymes = breaking down outer layer of egg
Nucleus = contains genetic information

Question 23

What is meant by “specialised”?

Answer 23

Physical or chemical changes

Being suited to a specific purpose

Question 24

How are root hair cells adapted?

Answer 24

Surface area = movement of water into cell
Large Permanent vacuole = speeds up osmosis
Mitochondria = transport energy needed for active transport

Question 25

How are photosynthetic cells adapted?

Answer 25

Chloroplast = photosynthesis Positioned into layers = absorb as much light as possible Large permanent vacuole = keeps cell rigid

Question 26

How are xylem cells adapted?

Answer 26

Cells die = form hollow tubes to allow water and mineral ions to move through them Rings of lignin = strong to withstand pressure

Question 27

How are Phloem cells adapted?

Answer 27

Sieve plates = carry dissolves food up and down tubes | Lose internal structures = supported by companion cells and move dissolves food

Question 28

What is the definition of Diffusion?

Answer 28

The spreading out of particles in a solution or gas resulting in the net movement from an area of high concentration to an area of low concentration, down the concentration gradient

Question 29

What are the two factors affecting diffusion?

Answer 29

Temperature | Concentration

Question 30

How does concentration affect Diffusion?

Answer 30

If there's a big concentration difference, diffusion is quick If there's a small concentration difference, diffusion is sow Particles move towards area of low concentration Difference between 2 areas is the concentration gradient The bigger difference, the steeper the concentration gradient

Question 31

Example of diffusion

Answer 31

Gas exchange: CO2 moves out from body cells into red blood cells. Then back into the air in the lungs by diffusion down the concentration gradient.

Question 32

Osmosis definition

Answer 32

The movement of water from a dilute to a more concentrated solution through a partially permeable membrane that allows water to pass through

Question 33

What does it mean if the solution is dilute or concentrated?

Answer 33

``` Dilute = high concentration of water, low concentration of sugar Concentrated = high concentration of sugar, low concentration of water ```

Question 34

Isotonic

Answer 34

Internal and external concentration are the same

Question 35

Hypertonic

Answer 35

Solution outside cell is higher than internal

Question 36

Hypotonic

Answer 36

Solution outside cell is lower than the internal concentration

Question 37

How does osmosis maintain the transport of water from a plant's roots to leaves?

Answer 37

Water enters roots by osmosis Water progresses from cell to cell Water moves up the plant Eventually reaches leaves or travels by xylem

Question 38

What is meant by the term Turgid?

Answer 38

Plants surrounding fluid is hypotonic to cytoplasm | Has lower concentration of solutes and higher concentration of water

Question 39

What is meant by the term Turgor?

Answer 39

Solution surrounding cell is hypertonic to cell Water leaves Wilts

Question 40

What is meant by the term Plasmolysis?

Answer 40

Even more water leaves Vacuole and cytoplasm shrink Cell membrane pulls away from cell wall

Question 41

Investigating osmosis in plants method

Answer 41

1) Prepare sugar solutions and select range you want to use to measure them. 2) Set up multiple boiling tubes with each of these solutions and one with distilled water for the controlled variable 3) Label each tube with its concentration 4) Draw a table before experiment 5) Weigh all of the potato's masses before putting in cylinder and then again after 6) For each sugar concentration repeat the investigation with each potato cylinder 7) Calculate the mean using all experiments ignoring anomalies 8) If the sugar concentration is higher outside than inside the potato, it will weigh more, water will move in. 9) Take care with scalpel, wear eye protection when wearing chemical solutions, do not cut potato towards hands

Question 42

Active transport definition

Answer 42

Moves substances from a more dilute solution to a more concentration solution

Question 43

How does active transport use energy?

Answer 43

Uses energy released from food in respiration to provide the energy required

Question 44

Describe how water moves from the soil to the leaf

Answer 44

``` Water moves into the roots via osmosis Water moves from the root hair cells into the xylem via osmosis Water moves up the plant via the xylem Evaporation of water from leaves Produces tension and pulls on the water This is the transpiration stream ```

Question 45

What's the difference between the Phloem and Xylem?

Answer 45

``` Xylem = transports water via transpiration Phloem = transports mineral ions and nitrates via translocation ```

Question 46

Adaptations for increasing the rate of diffusion

Answer 46

Short diffusion distance Big concentration difference Large surface area

Question 47

How are the lungs adapted for diffusion?

Answer 47

* (large surface area, alveoli, thin membrane, high diffusion rate, high gas exchange rate) * Alveoli have a large surface area * Capillaries are thin, one cell thick are close to the alveoli which provides short diffusion path for O2 and CO2 * Lungs are ventilated, bring in (fresh) oxygen and remove carbon dioxide, maintaining a concentration gradient * Large capillary network (around alveoli) and good blood supply which removes oxygenated blood quickly * Brings CO2 to the lungs quickly maintaining a concentration gradient