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AQA GCSE Biology > Organisation > Flashcards

Flashcards in Organisation Deck (116):

What is tissue?

A tissue is a group of similar cells that work together to carry out a particular function. It can include more than one type of cell.


What are some examples of tissues in mammals?

-Muscular tissue (contracts)
-Glandular Tissue (makes and secretes chemicals)
-Epithelial Tissue (covers some part of body)


What is an organ?

A group of different tissues which work together to perform a certain function


What tissues are the organs in the stomach made of?

-Muscular Tissue moves stomach wall to churn food
-Glandular Tissue makes digestive juices to digest food
-Epithelial tissue covers outside and inside of stomach


What is an organ system?

A group of organs working together to perform a particular function


Name the human organ systems:

-digestive system
-Circulatory system
-Respiratory system
-Excretory system
-Nervous system
-Reproductive system
-Digestive system
-Endocrine system
-Lymphatic system
-Immune system
-Muscular/skeletal system


"Organ systems work together to make _____"

Entire Organisms


What needs to happen inside your body and cells for you to work?

Chemical reactions to get the right amount of substances


Why are enzymes useful?

They act as a biological catalyst


Define Catalyst:

A substance which increases the speed of a reaction without being changed or used up in the reaction. Lowers activation energy required for a reaction.


What are enzymes made of?

Enzymes are all large proteins and all proteins are made up of chains of amino acids. These chains are folded into unique shapes, which enzymes need to do their jobs


What do chemical reactions with enzymes usually involve?

Substrates being split apart(metabolic) or joined together(catabolic)


What is the name of the place where the substrate fits into the enzyme?

Active site


Why do enzymes usually only catalyse one specific reaction?

Because for an enzyme to work, the substrate has to fit into its active site. If the substrate doesn't match the enzymes active site, then the reaction won't be catalysed


What is the "induced fit" model of enzyme action?

Where the active site changes shape a little as the substrate binds to it to get a tighter fit.


How does an enzyme become denatured with temperature?

Increasing the temperatures, increases the rate of a reaction at first. However, if it gets too hot, some of the bonds holding the enzyme together break. This changes the shape of the enzymes active site, so the substrate won't fit any more.


What condition, other than temperature effects the functionality of an enzyme?

Ph. If it is too high or low, the Ph interferes with the bonds holding the enzyme together. This changes the shape of the active site rendering the enzyme denatures


What is rate a measure of?

How much something changes over time


What is the formula to calculate the rate of a reaction where an experiment measures how much something changes over time?

Rate of Reaction = Change(amount of product formed) ÷ time (cm3/s)


What is the formula to calculate the rate of a reaction when time is measured?

Rate = 1000 ÷ time (s-1)


What are the three types of muscle cells?

Cardiac muscle cells, Skeletal muscle cells, Smooth Muscle Cells


What are the main organs in the digestive system in chronological order?



What digestive process happens in the mouth?

chewing (mechanical) increases surface area of food to increase digestion by enzymes in the mouth (amylase)


What digestive process happens in the oesophagus?

peristalsis (contracts and relaxes to push food down)


What digestive process happens in the liver?

Bile is produced (stored in gall bladder) which goes down the bile duct and into duodenum


What digestive process happens in the duodenum?

pancreatic produced enzymes operate in the duodenum-amylase,protease,lipase


What digestive process happens in the ileum?

glucose,minerals and nutrients are absorbed


What digestive process happens in the in the colon?

water is absorbed as the bloodstream needs it


What digestive process happens in the rectum?

Faeces is stored there until it is ready to pass out of anus


What does amylase do?

Catalyses the breakdown of starch into simple sugars e.g. glucose


What does protease do?

Catalyses the breakdown of protein into amino acids


What does lipase do?

Catalyses the breakdown of lipids into fatty acids and glycerol


How does the substrate concentration affect the rate of a reaction?

Increased substrate concentration results in a faster rate of reaction up to certain point where this rate plateaus


Why does the rate of reaction/concentration of substrate graph plateau?

Because of limiting factors. This could be enzyme concentration or temperature for example.


How does the enzyme concentration affect the rate of a reaction?

Increased enzyme concentration results in a faster rate of reaction up to certain point where limiting factors come into play


How do you test for starch?

Add iodine solution. If starch is present, the iodine will turn from brown/orange to a blue-black colour


How do you test for reducing sugars?

Add Benedict's solution (10 drops) to food sample in a test tube and place tube in a water bath(75 deg) for 5 minutes. If sugar is present it will produce a brick-red or yellow or green precipitate depending on how much sugar is in the food.


How do you test for protein?

Add biuret agent(2cm^3) to sample(2cm^3) and gently shake. If protein is present, the soltution will turn from blue to pink or purple .


How do you test for lipids?

Add three drops of Sudan III stain solution to the test tube with the sample(5cm^3) and gently shake. If lipids are present, the mixture will separate into two layers, the top layer will be bright red.


What is the danger with heating the boiling tube with Benedict's solution testing for sugars?

If the tube is boiled for a long time, the starch present may break down into sugar and test positive


Describe and explain the lock and key theory?

The theory explains why enzymes are specific because both the substrate and enzyme have a unique shape like a lock and key. The key represents the substrate and the lock represents the enzyme's active site. Only the substrate with the specific shape that fits exactly into the active site of the enzyme will form an enzyme-substrate complex.


After a reaction with an enzyme, what leaves the active site?

The product


What is denaturing of an enzyme?

Permanently changing the shape of an enzyme so it no longer compliments its substrate


What is the importance and function of the lungs?

The lungs are important as a gas exchange organ. It is where oxygen is able to diffuse into the blood, and carbon dioxide is excreted.


How are the lungs adapted for gas exchange?

-Have millions of alveoli (small air sacs) to increase the surface area
-Good blood supply (capillaries) reducing the diffusion distance of the gases
-The lungs are ventilated when we breathe to maintain a high concentration gradient of oxygen


What is the importance and function of the heart?

The heart is important because it transports oxygen, carbon dioxide and other important molecules through the body by pushing blood. It is a muscular pump.


What controls the heart beat?

A small group of cells called a pacemaker found in the right atrium. They initiate the contraction of the heart muscle with small electrical impulses.


Describe what happens during a heart beat sequence:

The atria contract, forcing blood into the ventricles. Then, the ventricles contract forcing blood into the arteries (pulmonary artery and aorta).


What is the function of the valves in the heart?

They prevent blood going the wrong way in the heart


What side of the heart has thicker muscle and why?

The side with the left atrium and ventricle so that more force can be applied to push the blood further


What separates the two sides of the heart, preventing oxygenated and non-oxygenated blood contamination?

The septum


What carries the oxygenated blood from the lungs into the heart?

The pulmonary vein


What carries the oxygenated blood from the heart to the body?

The aorta


What carries the de-oxygenated blood from the body into the heart?

The Vena Cava


What carries the de-oxygenated blood from the heart to the lungs?

The pulmonary artery


What type of arteries are the heart covered in which provide the heart muscle with oxygen?

Coronary arteries


Describe arteries:

Arteries are blood vessels which carry blood away from the heart. This means they are carrying blood under high pressure and this is why they need thick walls and have a narrow lumen. The walls contain elastic fibres and smooth muscle to withstand the high pressure of the blood and to exert force to move the blood.


Describe veins:

Veins are blood vessels which carry blood to the heart. They carry blood under a lower pressure which means they have thinner walls and larger lumens. Veins also have valves in them to stop blood going backwards (back flow).


Describe capillaries:

Capillaries are the smallest type of blood vessel in the body, they are only one cell thick. Their job is to enable the exchange of substances between the blood and surrounding tissues. Their thinness makes for a short diffusion distance for exchange of nutrients. Their walls are also permeable which allows substances in and out of the vessel. (ie.white blood cells)


What are the four main components of blood?

-Red blood cells
-White blood cells


Describe red blood cells:

They contain a red pigment called haemoglobin which binds to the oxygen and transports it from the lungs to body cells. They have no nucleus for more cytoplasm and therefore haemoglobin space. They are a biconcave shape to create large surface area to volume ratio for oxygen diffusion. Flexible cells to squeeze through capillaries.


Describe white blood cells:

These are the cells which protect the body against infection with microorganisms and pathogens. They are part of the immune system. Some produce antibodies and antitoxins and some undergo phagocytosis


Describe plasma:

The liquid which carries blood cells, platelets, nutrients, carbon dioxide, urea, hormones, proteins and anitbodies and antitoxins


Describe platelets:

Small cell fragments that help to form blood clots at wound sites, preventing excess blood loss and entry of pathogens. They have no nucleus.


What are the similar features of all leaves which allow them to do their function?

-Large surface area (absorb light rays)
-Thin shape (allow easy gas diffusion in and out)
-Many chloroplasts (absorb light energy for photosynthesis)
-Veins (support leaf but also carry water to the leaf and sucrose away from it)


Name the structures in a plant cell:

-Waxy cuticle
-Upper epidermis
-Palisade mesophyll
-Spongy mesophyll
-Vascular bundle
-Guard cells


What is the job of the waxy cuticle? How does it fulfil this role?

It prevents water from evaporating as the plant needs it. The waxy cuticle is waterproof which makes this happen.


What does the upper epidermis do? Does it have many chloroplasts?

The upper epidermis makes the waxy cuticle. It has no chloroplasts due to the long diffusion distance for carbon dioxide to reach it


What happens in the palisade mesophyll?

Lots of photosynthesis as it is packed with chloroplasts


What makes the spongy mesophyll good at its function?

It has large air spaces to allow gases to diffuse easily


What is the vascular bundle comprised of?

Phloem and Xylem cells (from the transport system)


What happens at the stomata?

Gas exchange (stomata is a hole on the underside of the leaf which can open and close)


What opens and closes the stomata for gas exchange?

Guard cells


How do guard cells open and close the stomata?

When the guard cells are plasmolysed, the stomata is shut but when they are turgid, the stomata is open.


What prevents guard cells from opening and allowing too much water to be lost from the leaf at night?

The chloroplasts in the cells which detect when it's day or night (sunlight)


What is transpiration?

The evaporation of water from a leaf


What happens when a plant loses too much water?

The individual cells will plasmolyse so the plant loses rigidity. This is called wilting.


Name the differences in transport systems between plants and animals:

-Plants use phloem and xylem tubes//animals use blood vessels
-Plants use sap//animals have blood
-Plants have a transpiration stream//animals have a heart to pump the blood


What are xylem cells and what is their function?

They are dead cells which form hollow tubes as each cell has no end walls. They are lignified to make them strong. They transport water and ions up from roots to leaves.


What are phloem cells and what is their function?

They are cells which form tubes to carry food (sugars) around the plant. Their cell walls break down to form sieve plates so food can move up and down easily and they lose lots of their internal structures so there is more room for dissolved food


How does the transpiration stream work?

Water evaporates in the leaf from the surface of the mesophyll cells and will then diffuse out of the stomata. This decreases the pressure inside the leaf. As a result, water is pulled into the leaf from the xylem. This then pulls on the column of water in the xylem.


What factors affect the rate of transpiration?

-Wind speed


How does temperature affect the rate of transpiration?

More thermal energy means more evaporation of water


How do the stomata affect the rate of transpiration?

More stomata means more surface area for diffusion


How does humidity affect the rate of transpiration?

The more humid the air outside the leaf, the lower the concentration gradient and therefore, rate of diffusion (and transpiration)


How does wind speed affect the rate of transpiration?

Still air allows small packets of humid air to settle and from by the stomata, reducing the concentration gradient. The introduction of wind stops this happening, increasing the transpiration rate


What type of circulatory systems do humans and other mammals have?

A double circulatory system (blood passes through heart twice on one circuit) due to two separate transport systems


What is coronary heart disease caused by?

Narrow or blocked coronary arteries due to layers of fatty materials building up


How could coronary heart disease be treated?

-Using a stent
-Bypass surgery
-Taking statins


What is the function of bile?

It has an alkaline pH to neutralise stomach acid. It also breaks down large fat globules into small droplets (emulsifying).


What is the use of protein in the human body?

It is used for forming new tissues, enzymes and hormones


What is the use of lipids in the human body?

Providing energy and building new cell membranes and hormones


What is the use of carbohydrates in the human body?

Provide energy


Digestive enzymes are released by glands in the body, where is amylase produced?

In salivary glands and the pancreas


Where is protease produced?

Stomach, pancreas and small intestine


Where is lipase produced?

Pancreas and small intestine


What is digestion?

The breaking down of large insoluble food molecules into small soluble food molecules


What are the disadvantages to using a stent?

-Risk of complications during operation
-Risk of infection from surgery
-Risk of thrombosis (blood clot near stent).
-It cannot be used for badly blocked arteries either.


What are the disadvantages of using statins?

-Long term drug which are required to be taken regularly
-Can have some negative side effects which can be serious (kidney failure, memory loss and liver damage)
- Effect of statins isn't instant


What is translocation?

The mass movement of sucrose and amino acids from a leaf through a phloem cell to the sink of a plant where it is stored and used for growth and energy in respiration


What don't phloem cells contain? What is used to replace the function of those features?

Phloem cells have no cytoplasm or organelles. They rely on companion cells which provide energy


How does the sap in the phloem cells move about?

Up and down the cells, transporting the nutrients from the source to the sink (where nutrients are stored/used)


What piece of equipment can be used to measure the rate of transpiration?

A potometer


Xylem vessels carry water and minerals, what are the mineral ions and water used for?

Mineral ions are used to make protein and water is used in photosynthesis and keeping the plant rigid


What sheet of muscle separates the lungs from the abdomen?



What does a stent do?

Stents are wire mesh tubes which are inserted into arteries. They keep the arteries open, push fatty deposits out of the way of blood flow, and make sure the blood can pass to the heart muscles


What are the advantages of a stent?

-Keyhole surgery so small wound
-Local anaesthetic so fewer risks
-Quick recovery after surgery
-Quick and relatively cheap surgery
-Lowers risk of heart attack
-Effective for a long time


What do statins do?

They are drugs which reduce LDL cholestrol (bad lipid) in blood stream which reduces fatty deposits inside arteries


What are the advantages of statins?

-Reduce LDL cholestrol which reduces risk of strokes, coronary heart disease and heart attacks
-Increase HDL cholestrol in bloodstream (removes bad cholestrol and serves as essential lipid for functioning)
-Can help prevent some other diseases


What is bypass surgery?

A small piece of blood vessel is taken from elsewhere in the body and joined to coronary artery around the blockage to provide an alternative route for blood to flow


What are the advantages of bypass surgery?

-Prevents coronary heart disease
-Can be used where stents are ineffective
-Can be used to prevent multiple blockages


What are the disadvantages of bypass surgery?

-Requires a riskier general anaesthetic
-Long expensive surgery
-Recovery period is long
-Risk of wound infection


What are the advantages of a double circulatory system?

-Deoxygenated and oxygenated blood are separated
-Blood pressure is higher particularly to the body
-Higher blood flow to body tissues


How can heart block be treated?

Using an implanted pacemaker which produces an electric current to keep the heart beating regularly


Why is transpiration important?

-Transpiration pull
-Cooling of the plant
-Plant structure


How does haemoglobin help pick up, transport and release oxygen?

Oxygen diffuses into the red blood cells and haemoglobin has an affinity for it and binds to it creating oxy-haemoglobin. This happens in areas of high oxygen concentration. In conditions of low oxygen concentration, the oxy-haemoglobin breaks down and releases the oxygen.