Cellular biology Flashcards
basic overview of Photosynthesis + both types of equations
Photosynthesis is the process in which plants use sunlight and carbon dioxide to produce glucose and oxygen.
Carbon dioxide + water —light—> Glucose + oxygen
6CO2 + 6H2O –light–> C6H12O6 + 6O2
how does temperature affect photosynthesis
Temperature is a factor that affects oxygen production, as warmer temperatures are more favourable than colder temperatures. This means enzymes can collide more with substrates, and more chemical reactions can occur. However, if the temperatures increase too much, the enzymes may denature, resulting in the active site changing shape, in which case chemicals reactions will slow or stop photosynthesis
How does CO2 conc affect the rate of photosynthesis?
because carbon dioxide is combined with hydrogen ( in the light-independent reaction), to form glucose, the final product of photosynthesis
Where and how does water enter a plant
Water in the soil enters the root of the plant/ tiny root hairs through the semi-permeable membrane. Water enters via osmosis. Osmosis is the diffusion of water across a semi-permeable membrane from an area of high water conc to an area of low water conc. Osmosis is passive and therefore does not require energy. for water to enter the root cells, the root cells must have a lower water concentration than the surrounding soil
Where and how does CO2 enter a plant?
CO2 enters through the stromata via diffusion. CO2 (g) moves from an area of high conc to an area of low conc inside the leaf. Its passive, so no energy is required
how does different wavelengths affect the oxygen/ photosynthesis rate
Different wavelengths/ colours of light provide different amounts of energy/ photons. This means less hydrogen is split and less combine to form glucose.
how does light intensity affect O2 production
Oxygen is derived from the water absorbed by the plants roots. Oxygen is produced by the light-dependent reaction, in which sunlight splits water molecules, therefore oxygen production is dependent on light.
what is limiting factors for photosynthesis
The rate of photosynthesis will always correspond to the factor necessary for photosynthesis that is in the least supply. These then become limiting factors; that is, those factors also need to bring about further increase in the rate
what is Anaerobic respiration
Anaerobic occurs in the cytoplasm of a cell-glucose is broken down into lactic acid and ATP(energy); No oxygen is present, therefore less energy (2ATP) is produced compared to aerobic
Disadvantages of anaerobic
Anaerobic is less efficient and unsustainable as the lactic acid build-up causes cramps and stops the muscles from working properly , if not removed from the cell, lactic acid becomes toxic
Advantages of anaerobic respiration
Anaerobic produces ATP very quickly because it does not require oxygen. If oxygen is temporarily unavailable/low in the cell, such as explosive exercise, cells still get the energy needed to function.
What is aerobic respiration
Occurs in the cytoplasm and mitochondria aerobic respiration is when glucose is broken down in the presence of oxygen to form carbon dioxide, water and ATP
Advantages of aerobic respiration
Oxygen is present, so more energy (36 ATP) is produced compared to anaerobic, and therefore more sustainable;e and efficient. Lactic acid/ ethanol ( which can be toxic) is not produced
Disadvantages of aerobic respiration
Aerobic respiration requires oxygen, so ATP is produced slower. E.g. it would be more advantageous to anaerobically respire. However, it is not sustainable
Osmosis in Seawater
water is lost from the fish as the fish’s body has a higher concentration of water compared to surrounding sea water. Salt water is drunken by the fish to replace water lost from osmosis, however, Na+ and Cl- (solutes dissolved in water) are not wanted
Active transport
active transport is the movement of substances across a membrane against a concentration to an area of high concentration. it requires energy/ ATP. it occurs in the cell membrane
What is the enzyme structure
an enzyme is made up of proteins and have an active site where the substrate binds
how does an enzyme work
An enzyme works by lowering the activation energy in a reaction. Its active site is substrate specific. Once the enzyme-substrate complex has formed. The active site changes shape to either break apart or form chemical bonds needed for the reaction
What is an enzyme inhibitor
An inhibitor would stop the enzyme from binding with its substrate by changing the active site’s shape. This would slow or stop biological reactions
how does the position of the chloroplast maximise photosynthesis
The central vacole ensures the chloroplasts are near the outer edge of the cell. This allows the chloroplast to absorb more light and creates a shorter distance for H2O and CO2 to travel from outside the cell to the chloroplast, therefore allowing P/S to occur at a faster rate. The faster the CO2 and H2O that can be absorbed by diffusion and osmosis, the sister the P/S rate is
how does the outer membrane of a chloroplast maximise photosynthesis
the outer membrane is clear allowing light to pass through it to the thylakoid membrane/grana stacks where the light dependent phase takes place. these membrane are filled with chlorophyll which is needed to drive the light phase, breaking dow water into H+ allowing the next phase to occur. The light phase provides energy/ATP and H+ to drive the next phase to occur,so without the light phase no photosynthesis can occur
DNA replication, with an example
The purpose of DNA replication is to produce two identical copies of the cell’s DNA., the purpose being for cell growth and repair. DNA must be replicated before mitosis via a semi-conservative replication, so that the new cell has the correct AMOUNT of DNA and has all genetic information to carry out its function. For example a new intestinal cell must have DNA information needed to produce the digestive enzymes needed to do its job. Without the DNA information required to carry out their function, these cells will die if the organism cant grow
The cell cycle with an example
Involve both the production of new cells and the growth of these cells. Therefore the organism grows as more new cells are produced through mitosis. When these new cells get larger, this also causes growth. For example, at the root tip, mitosis produces new cells and the enlargement of these cells causes the root to grow. The new cells can only grow to a certain size before the surface area: volume ratio becomes to small to support rapid transport. Therefore it must carry out mitosis in order to maintain a large SA:V ratio
what is light dependent stage and where does it take place
light-dependent stage takes place in the thylakoid membrane within the chloroplast. Light energy is absorbed by the pigment chlorophyll. This light energy splits the water molecules into O2 and H+. Hydrogen “goes: to the light-independent process, while oxygen is excreted ( via the stomata on the leaves
