B2.1 Supplying the Cell - Part 1

Question 1

<p>What is diffusion?</p>

Answer 1

<p>The passive net overall movement from a region of high concentration to a region of low concentration.</p>

Question 2

<p>Particles move ....... and ........ by diffusion.</p>

Answer 2

<p>Particles move <u>constantly</u> and <u>randomly</u> by diffusion</p>

Question 3

<p>What key gases do we need to diffuse from our lungs to our blood stream?</p>

Answer 3

<p>Oxygen</p>

Question 4

<p>What key nutrient do we need to diffuse from our blood stream to our muscle cells?</p>

Answer 4

<p>Glucose</p>

Question 5

<p>What factors affect diffusion?</p>

Answer 5

<p>Surface area</p>

<p>Temperature</p>

<p>Concentration gradient</p>

<p>Distance</p>

Question 6

<p>Name key adaptations of the body to facillitate diffusion?</p>

Answer 6

<p><u>Alveoli</u></p>

<ul> <li> <p>They are very thin - small distance to diffuse over</p> </li> <li> <p>They are covered by a network of fine capillaries - diffuse straight into bloodstream, maintainsconcentration gradient</p> </li> <li> <p>They are moist</p> </li> <li> <p>They have a large combined surface area.</p> </li></ul>

<p></p>

<p><u>Small intestines</u></p>

<ul> <li>Villi & Microvilli - increases surface area, therefore volume that can be absorbed</li> <li>Good blood supply – substances diffuse straight into the bloodstream, maintains concentration gradient</li></ul>

Question 7

<p>What role does diffusion play in nerve impulses?</p>

Answer 7

<ul> <li>Diffusion allows a nerve impulse to travel between two neurones at a synapse</li> <li> <p>Neurotransmitter molecules diffuse from vesicles towards the neurotransmitter receptors, moving from an area of high concentration to low concentration.</p> </li></ul>

Question 8

<p>How the is placental organ is adapted to maximise diffusion?</p>

Answer 8

<p>A large surface area between it and the uterus wall.</p>

<p>Villi (finger like projections that extend into the uterus wall), which furtherincreasethe surface area of theplacenta.</p>

<p>A rich supply of maternal blood vessels.</p>

Question 9

<p>What role does diffusion play in enabling photosynthesis?</p>

Answer 9

<p>•Carbon dioxide diffuses in through the stomata.</p>

<p>•Oxygen and water diffuse out of the stomata</p>

<p>•During photosynthesis, the level of CO₂ is low inside the leaf, creating a big concentration gradient so CO₂ diffuses into the cell</p>

Question 10

<p>Define osmosis.</p>

Answer 10

<p>Osmosis is a special type of diffusion. The diffusion of water molecules across a partially (selectively) permeable membranefrom an area of high water potential to an area of lower water potential (down a concentration gradient).</p>

Question 11

<p>What is meant by 'hypertonic'?</p>

Answer 11

<p>A fluid has a higher osmotic pressure (lower water potential) than a particular fluid, typically a body fluid or intracellular fluid.</p>

Question 12

<p>What is meant by the term 'hypotonic'?</p>

Answer 12

<p>A fluid has a lower osmotic pressure (lhigher water potential) than a particular fluid, typically a body fluid or intracellular fluid.</p>

Question 13

<p>Why is important to plant cells in particular?</p>

Answer 13

<p>The vacuole which helps mantain the cells structureis filled by osmosis.</p>

Question 14

<p>Explain the term 'turgid'.</p>

Answer 14

<p>When water enters the cell by osmosis and fills the vacuole. This pushes against the cell wall, making the cellturgid.</p>

Question 15

<p>Explain the term 'flaccid'.</p>

Answer 15

<p>Whenwater moves out of the cell by osmosis, the vacuole shrinks and the cell becomesflaccid</p>

Question 16

<p>Thishappens if too much water leaves a plant cell, and the cytoplasm moves away from the cell wall.</p>

Answer 16

<p>Plasmolysis</p>

Question 17

<p>What is 'lysis'?</p>

Answer 17

<p>When an animal cell is placed in a hypotonic solution causing too much water to enterthe cell by osmosis and the cell to swell and burst.</p>

Question 18

<p>What is 'crenation'?</p>

Answer 18

<p>When an animal cell is placed in a hypertonic solution causing too much water to leave the cell by osmosis and the cell to shrink and shrivel.</p>

Question 19

<p>Osmosis takes place over a...</p>

Answer 19

<p>Selectively/semi-permeable membrane</p>

Question 20

<p>Define active transport.</p>

Answer 20

<p>The transport of particles from an area of low concentration to an area of high concentration, against a concentration gradient using ATP (energy).</p>

Question 21

<p>What are carrier proteins?</p>

Answer 21

<ul> <li>Protiens embembedded within the cell surface membrane.</li> <li>They bind with useful molecules and then use ATP to rotate or change shape to transport the molecule into the cell.</li> <li>Allow the transport of useful molecules against a concentration gratient</li></ul>

Question 22

<p>State an example of active transport in plants.</p>

Answer 22

<p>Root hair cells - Transport of mineral ions from low concentration in the soil to higher concentration in the root hair cell.</p>

Question 23

<p>State two examples of active transport in animals.</p>

Answer 23

<ol> <li><u>Nerve cells</u> - active transport used to pump sodium & potassium ions required to create nerve impulses</li> <li><u>Digestion</u> -active transport used to transport the final products og digestion into the bloodstream through the villi</li></ol>

Question 24

<p>Why do cells that carry out active transport contain a lot of mitochondria?</p>

Answer 24

<p>Mitochondira produce energy and energy is required for active transport to take place.</p>