Biology Flashcards
Magnification
Image size/Actual size
Factors that affect rate of diffusion
- Surface area
- Temperature
- Concentration gradient
- Distance
Turgor pressure
The pressure of the water pushing against the cell wall. Helps plants to maintain their structure.
Turgid - fat
Flaccid - normal
Plasmolysed - ryan
Cell membrane
- Made of fat and proteins
- Holds together the cell contents, such as the nucleus and cytoplasm
- Partially permeable
Cytoplasm
- Jelly-like substance; its main component (around 70%) is water
- It fills all the space inside the cell (except the space that is occupied by the nucleus and other structures)
- Many chemical reactions take place in the cytoplasm
Nucleus
- A rounded organelle
- Located in the centre of animal cells, and towards the edge of plant cells
- Contains chromosomes, which are made of DNA
- DNA carries the genetic information of the organism
- The nucleus controls all the activities of the cell (the cell’s metabolism)
Cell wall
- The outermost structure in all plant cells
- It is mostly made of cellulose fibres. Slightly elastic.
- Provide shape and support to the cell and prevent it from bursting when it absorbs water
- This is how tall trees can keep upright even though they do not have a skeleton: the strong cellulose cell walls of the individual cells support the tree
Vacuole
- Fills most of the space inside the plant cell.
- It also contains some chemicals, such as mineral salts, lipids, proteins and pigments. (Pigments are substances that give colour to flowers and other structures.)
- It helps the cell to stay rigid.
- Within the vacuole, substances can be stored and waste materials can be broken down.
Chloroplasts
- Green oval structures
- Found in cytoplasm
- Green because of chlorophyll - Traps light energy and converts it
- Starch grains inside for food store
Test for reducing sugars
- Benedict’s solution at 80 to 100 degrees
- Positive result: Changes from light blue to green, then yellow, and red.
- Negative result: Remains blue
Test for starch
Iodine solution
Positive result: Dark blue
Negative: Remains brown
Test for fats and oils
- Ethanol used to dissolve fat or oil
- Filtered and filtrate is added to water
Positive: Cloudy white precipitate in water
Negative: Transparent
Test for protein
- Biuret solution
Positive: Purple
Negative: Remains blue
Adapations of leaves
- Large surface area (take in a lot of sunlight and CO2)
- Light does not travel far
- Stomata allows gas exchange
- Xylem and phloem close to mesophyll cells (supply water to cells and remove products)
- Stem and leaf stalks (hold leaves out for sunlight and CO2)
Use of glucose in plants
- Used instantly to meet energy demands
- Used to transport chemical energy to where it is needed
- Converted into long chains known as starch for storage
- Glucose is highly reactive so it is formed into sucros for transport
Waxy cuticle
Stops water from evaporating from the leaf
Guard cells
Open or close the stomata to allow diffusion also contains chloroplasts
Stomata
Small openings on the underside that allow diffusion of gases in and out of the leaf
Epidermis
Thin layers of cells that protect the inner cells and do not contain cholorplasts
Palisade mesophylll layer
Contains closely packed cells that have lots of chloroplasts
Spongy mesophyll layer
Cells are loosely spaced in this layer to allow diffusion of gases throughout the leaf
Xylem
Carries water from the roots to the leaf
Fats
Found in: Avocado, olive oil, nuts
Uses: Long-term energy supply and insulation
Phloem
Carrie sucrose away from the leaf
Nitrate ions
Synthesis of amino acids
Magnesium ions
Synthesis of chlorophyll
Carbohydrates
Found in: Rice, bread, potatoes, pasta
Use: Short term supply of energy
Proteins
Found in: Meat, fish, eggs, milk
Uses: Growth and repair
Vitamin C
Found in: Citrus fruits, green vegetables, potatoes
Uses: Healthy skin, teeth, and gums. Keeps lining of blood vessels healthy
Vitamin D
Found in: Fish, eggs, liver, cheese
Uses: Strong bones and teeth
Calcium
Found in: Milk and eggs
Uses: Needed for strong teeth and bones, and involved in clotting of blood
Iron
Found in: Red meats, liver and kidneys, leafy green vegetables(spinach)
Uses: Needed for production of haemoglobin in red blood cells
Fibre
Found in: Leafy vegetables, unrefined grains (brown rice)
Uses: Prevents constipation
Water
Uses: Necessary for all life processes
Scurvy
Lack of vitamin C
Swollen, bleeding gums, and slow healing wounds
Vitamin D deficiency
Cannot absorb and use the calcium they need
Soften and deformed bones
Iron deficiency
Anaemia (reduction in number of blood cells)
Kwashiorkor
Severe form of protein-energy malnutrition.
Enough energy from food, but diet does not contain enough protein-rich food.
Body begins to swell, because too much liquid stays in the body.
Marasmus
An inadequate intake of energy from all nutrients.
Symptoms of marasmus include stunted growth, and loss of fat and muscle mass leading to a wasted appearance.
Ingestion
Definition: Taking substances (food and drinks) into the body through the mouth
Location: Mouth
Mechanical digestion
Definition: Breaking down food down into smaller pieces without any chemical change to the food molecules
Location: Mostly mouth(chewing) but also the stomach
Chemical digestion
Definition: Breakdown of large, insoluble molecules into small, soluble molecules
Location: Mostly the small intestine but also the mouth
Absorption
Definition: Movement of digested food molecules and ions through the wall of the intestine into the blood
Location: Small intestine
Assimilation
Definition: Movement of digested food molecules from the blood into the cells of the body
Location: Whole body
Egestion
Definition: Passing out food that has not been digested or absorbed
Location: Rectum and anus
Adaptations of villi
- Large blood supply (blood capillaries in each villus so nutrients absorbed can be transported away quickly)
- Finger like projections called microvilli (increase the surface area of the small intestine so nutrients can be abosrbed more rapidly)
Thin layer of cells so the molecules do not travel far - Lacteals which carry fat droplets separately from the rest of the food molecules because fat does not dissolve in blood
Double circulatory system
Blood passes through the heart twice while completing a cycle around the body.
- Pulmonary circulation
- Systemic circulation
Heart has two left and right sides
Blood must flow through the heart twice in one circuit
Advantage of double circulatory system
- Oxygenated and deoxygeneated blood are kept separate
- Ensures efficient supply of oxygen
- Efficient supply of nutrients
- Lower pressure in pulmonary
- Prevents damage to lungs
- Allows more time for gas exchange
- Allows higher pressure in body
- Ensure efficient blood supply
- Allow filtration of kidneys for excretion
- Allow and maintain a high metabolic rate
Arteries
- Carry blood away from the heart.
- Thick, strong walls with a layer of smooth muscles - High blood pressure
- The flow of blood through the arteries is not smooth: the blood pulses through as the ventricle contracts and relaxes.
- The walls of the arteries contain elastic tissues that respond to the force of the blood, making the flow of blood smoother.
- The rhythmic changes in blood pressure in the arteries can be felt easily where an artery passes close to the surface of the skin; this is your pulse.
- The blood pressure in the arteries of the arm can be measured accurately by using a device called sphygmomanometer.
Capillaries
- Tiny blood vessel which allows the exchange of materials between the body cells and the blood.
- Wall of the capillary is extremely thin and is made up of only a single layer of cells.
- Capillaries are so narrow that blood cells must pass through them in single file.
Veins
- Veins are blood vessels that carry blood towards the heart.
- Flows slowly and smoothly - low blood pressure
- Thin walls and a relatively large internal diameter.
- Large veins of the body have valves within them, to ensure that the flow of blood is always towards the heart.
- Skeletal muscles in the body also help to push the blood in the veins towards the heart by squeezing them every time they contract.
- Exercise is important for good vein blood flow
Bronchitis
- Smoke damages the cilia in the trachea
- Dust and microorganisms become trapped in the mucus but the cilia cannot move it as many are damaged
- The goblet cells produce more mucus to make up for this but it builds up - bacteria grow in it
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Emphysema
- Smoke particles become suck in the alveolar walls
- Chemicals are secreted to remove the particles but also damage the alveolar walls
- Decreases the surface area reducing the efficiency of gas exchange
Nicotine
- Increase risk of high blood pressure
- Addictive
- Stimulant
- Decreases the elasticity of arteries so they cannot stretch and recover
- Increases the probability of blood clot being formed
Tar
- Burnt resinous material from tobacco
- Carcinogens that cause cancer
Hormones
Chemical substance which is produced by a gland and is carried by the blood. Hormones alter the activity of one or more specific target organs.
