Biology - B2

  • Created by: abbiedye
  • Created on: 20-06-18 10:20

What are cell organisations?

- Large multicellular organisms are made up of organ systems

- Similar cells make up tissues

- Tissues make up organs

- Organs make up organ systems

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What type of cells are organised into tissues?

Tissue - group of similar cells that work together to carry out a particular function


- Muscular tissue - contracts to move whatever its attached to

- Glandular tissue - make and secrete chemicals like enzymes and hormones

- Epithelial tissue - cover some parts of the body (inside the gut)

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What types of tissues are organised into organs?

Organ - group of different tissues that work together to perform a certain function


- Muscular tissue - moves the stomach wall to churn up food 

- Glandular tissue - makes digestive juices to digest food

- Epithelial tissue - covers the outiside and inside of the stomach

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What types of organs are organised into organ syst

Organ systems - group of organs working together to perform a function


- Glands - (pancreas and salivary glands) - produce digestive juices

- Stomach and small intestine - digest food

- Liver - produces bile

- Small intestine - absorbs soluble food molecules

- Large intestine - absorbs water from undigested food - faeces

Organ systems - organsims

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What are enzymes?

- Enzymes are large proteins - chains of amino acids

- They speed up reactions inside living things by acting as catalysts

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How do enzymes catalyse reactions?

- enzymes have special shapes so they can catalyse reactions

- enzymes only catalyse one specific reaction - unique shape

- 'lock and key'

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Why do enzymes need the right temperature and pH?

- too hot - 45 degrees - bonds holding the enzyme together break - change enzymes active site - 45 degrees = denatured

- too high / low pH - intefers with bonds holding the enzyme together - changes the shape of the active site - denatures

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Explain digestive enzymes

- starch, proteins and fats are big molecules

- they're too big to pass through the walls of the digestive system

- so digestive enzymes break these big molecules down into smaller ones

- these smaller, soluble molecules can easily be absorbed into the bloodstream

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What are carbohydrates converted into?

- Carbohydrases convert carbohydrates into simple sugars

- Amylase is a carbohydrase, it breaks down starch

- Made in - salivary glands, the pancreas, the small intestine

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What are proteins converted into?

- Proteases convert proteins into Amino Acids

- Protease = enzyme

- Made in - the stomach (called pepsin), the pancreas,  the small intestine

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What are lipids converted into?

- Lipases convert lipids into glycerol and fatty acids

- Lipase = enzyme

- Made in - the pancreas, the small intestine

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How does bile neutralise stomach acid?

- Produced in liver - stored in gall bladder - released into acidic small intestine

- Bile = alkaline - it neutralises and makes conditions alkaline and the enzymes work best in alkaline conditions

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Where are the different enzymes produced?

- Salivary glands - amylase enzyme in saiva

- Stomach - pummels food, protease enzyme (pepsin), acid - kill bacteria, right pH for protease

- Liver - produces bile - neutralises stomach acids + emulsifies fats

- Gall bladder - where bile is stored

- Pancreas - produces protease, amylase and lipase - released in small intestine

- Large intestine - excess water from food absorbed

- Small intestine - protease, amylase and lipase - complete digestion

- Rectum - faeces

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What are the different food tests?

- Benedicts test for sugars - turns from blue to green, yellow or brick-red

- Iodine solution for starch - turns from browny-orange to black or blue-black

- Biuret test for proteins - turns from blue to pink or purple

- Sudan III for lipids - top layer turns bright red

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How do the lungs work

- Air breathed in goes through the trachea - splits into two tubes called bronchi, one going to each lung

- The bronchi split into bronchioles which end at small bags called alveoli

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How do the alveoli carry out gas exchange?

- Blood passing next to the alveoli contains lots of carbon dioxide and very little oxygen

- Oxygen diffuses out of the alveolus (high concentration) into the blood (low concentration) alveolus

- Carbon dioxide diffuses out of the blood into the alveolus

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How does the heart's double circulatory system wor

- Two circuits

- Right ventricle - deoxygenated blood to the lungs to take in oxygen - then returns to the heart

- Left ventricle - pumps oxygenated blood around all other organs - the blood gives up its oxygen - deoxygenated blood returns to the heart

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How does the heart pump blood around the body?

1. Blood flows into two atria from the vena cava and pulmonary vein

2. Atria contract - blood into ventricles

3. Ventricles contract - blood into pulmonary artery and aorta - out of the heart

4. Blood flows to organs through arteries and returns through veins

5. Atria fill again and cycle starts over

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Circulatory system - The heart

- The heart is an organ with four chambers

- It is used to pump blood around the body

- The valves in the heart stop blood flowing backwards

- The heart also needs its own supply of oxygenated blood

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Circulatory system -Blood vessels

- Arteries carry blood under pressure (carry the blood away from the heart)

- Arteries branch into capillaries which carry blood close to every cell

- Capillaries join up to form veins that take blood back to the heart

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How do arteries, capillaries and veins work?

- Arteries - the heart pumps blood at a high pressure - artery walls are strong and elastic

- Capillaries - arteries branch into capillaries - close to every cell to exchange surfaces

- Veins - capillaries join up to form veins - blood is lower pressure - back to heart

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Circulatory system - Blood

- Red blood cells carry oxygen

- White blood cells defend against infection

- Platelets help blood clot

- Plasma is the liquid that carries everything in blood

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What is coronary heart disease and what are stents

- Coronary heart disease - coronary arteries get blocked by layers of fatty material causing restricted blood flow and lack of oxygen to the heart

- Stents - tubes inserted inside arteries - keep them open - they are effective (long time) but they can cause infection due to blood clots (thrombosis)

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What are statins?

- Statins reduce cholesterol (essential lipid) - excess = health problems / fatty deposit

Advantages -

 -reducing strokes, heart disease + heart attacks                                                                                 -increase 'good' cholesterol                                                                                                                 -prevent other diseases


 -long-term drug (forgotten)
 -negative (serious) side effects / kidney damage                                                                                 -effects aren't instant

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What methods can be used to prevent heart disease?

- Artificial heart - heart failure - ca pump blood - don't work as well -  drugs to thin blood - electric motor could fail - surgery - infection and bleeding

- Biological or mechanical valves - replace faulty valves - less drastic procedure - major surgery - blood clots

- Artificial blood - emergency - blood substitute - 'saline' -safe (no air bubbles) - gives time for patient to produce new blood cells

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What factors can affect your health?

Diseases interact - problems with immune system - communicable diseases - cancer + viruses and mental health + physical health problems

Factors - diet, stress, life situation

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What are the factors of non-communicable diseases?

Increased chance - lifestyle (developed areas), environment, interacting with others

Direct causes - smoking (lungs and heart), obesity (diabetes), too much alcohol (liver), exposure to radiation (cancer)

Non-communicable diseases - costly - human lives (shorter lifespan) - financial (NHS research)

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What is cancer?


Benign - stays in one place - isn't cancerous                                                                                        Malignant - break off into bloodstream - dangerous

Risk factor - smoking, obesity, UV exposure, viral infection and genetics  

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How are plant cells organised?

- Waxy cuticle - reduce water loss

- Epidermal tissue - transparent = light ca go through

- Palisade mesophyll tissue, spongy mesophyll tissue and epidermal tissue- gas exchange

- stomata and guard cells - respond to enironment changes

Xylem and phloem - deliver water and nutrients

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Transpiration and Translocation

Translocation - Ploem = food (dissolved sugars) and xylem = water and minerals

Transpiration - caused by the evaporation and diffusion of water from a plant's surface - drawn up from roots to leaves - constant transpiration rate / stream

Transpiration stream = roots to xylem to leaves

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What affects transpiration rate?

Light intensity - brighter = greater rate                                                                                                Temperature - warmer = greater rate                                                                                                    Air flow - stronger wind = greater rate                                                                                                  Humidity - drier = greater rate

Guard cells - adapted for gas exchange + water loss control                                                                 - plant has lots of water - stomata open - gases exchanged for photosynthesis                                 - short of water - stomata close                                                                                                             - more stomata on undersides - cooler - less water lost

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