Cell Biology🔬
What is a tissue?
A group of similar cells working together towards the same function
Which biological molecule can be tested for using Benedict's solution?
Reducing sugars
What is the balanced chemical equation for photosynthesis?
6CO2 + 6 H2O --> C6H12O6 + 6O2
What is the function of red blood cells?
To carry oxygen around the body
Where does anaerobic respiration occur in animals?
Cytoplasm
Net movement of water molecules from a region of higher water potential to a region of lower water potential down a water potential gradient across a partially permeable membrane
What is the function of lipids? (give 2)
Insulation, found in cell membrane, energy resource, speed up conduction of nerve impulses (myelin sheath)
What is the definiton of transpiration?
Evaporation of water from mesophyll cells into air spaces, and diffusion of water vapour out of the leaf through the stomata
Compare arteries and veins.
Arteries - thick walls, narrow lumen, no valves
Veins - thinner walls, wider lumen, valves present
What is the equation for anaerobic respiration in yeast?
C6H12O6 --> 2C2H5OH + 2CO2
Explain some adaptations of the root hair cell. (4 marks)
Root hair --> increases surface area for water absorption by osmosis
Lots of mitochondria --> present for aerobic respiration for energy for active transport of mineral ions
No chloroplasts --> no exposure to sunlight
Explain why large food molecules like protein must be digested to amino acids if its just going to be used to make protein again in the body
Smaller molecules (amino acids) are soluble and can be transported by the blood to areas it will be used.
Different proteins are made of different amino acids so the ones required by the body must be joined in the right order.
Compare and contrast the xylem and phloem.
Both have cell wall and cell membrane
Xylem cells are dead/hollow
Xylem has no adjacent cell walls/Phloem has sieve plates
Explain why blood is so important for transport.
Humans have a small SA:V, diffusion alone would not be efficient enough to tarnsport all of the required materials around the body, blood is important as it is used as a medium for transport
Nostril --> Nasal Passage --> Pharynx --> Larynx --> Trachea --> Bronchus --> Bronchiole --> Alveoli
Predict what happens to a plant cell in a concentrated sugar solution.
Plasmolysed
Cell wall detaches from cell membrane as the cytoplasm shrinks due to loss of water from the vacuole by osmisis
Explain how temperature affects enzyme activity.
Increase temp = high kinetic energy = more enzyme substrate collisions (complex) = more products but if temp too high = enzyme denatured = active site changes shape = no longer complementary = lower product formation
Explain how a water molecule from the soil is transpired by the leaf of the plant.
Osmosis into root hair cells, enters xylem, moves up xylem through transpiration stream (cohesion, adhesion, osmotic pressure), reaches the vascualar bundle of the leaf, and is then transpired out.
Explain how white blood cells help with infections
Phagocytes = phagocytosis (engluf and digest pathogens)
Lymphocytes = produces antibodies, these bind complementarily to antigens on the surface of pathogens and helps with the production of memory cells which saves this information for secondary immune response
What is the oxygen debt?
Anaerobic respiration creates lactic acid as a byproduct, which is toxic to the body. In order to remove lactic acid, the body requires oxygen. This means that the body has built up a need for even more oxygen. This is the oxygen debt
Explain how surface area to volume ratio affects exchange. Give 2 specific biological examples
Large surface to volume ratio increases the rate of exchange. This means there is less volume (small space) but lots of surfaces for particles to move across.
Eg:
Villi (high surface, low volume)
Alveoli (round and small, high surface area, low volume)
Bacteria (unicellular so large SA to volume ratio --> do not need transport systems)
Babies (small so large SA:V, loses heat easily)
A student eats some some pasta with meatballs. Explain what happens.
Mouth = chewing = amylase = digestion of starch to maltose
Peristalsis and Oesophagus
Stomach = churning = pepsin = digestion of proteins
Duodenum = Pancreatic juice = trypsin and lipase and amylase = digestion of proteins and fat and starch
Epithelial lining produces maltase = digestion of maltose into glucose
Ileum = villi = absorption (FA and Glycerol into lacteal/amino acids and glucose into capillaries) ALL carried to liver by HPV and then assimilated accordingly
What is the role of magnesium in plant growth? Predict what happens if plants lose magnesium.
Magnesium is important for chlorophyll
Low magnesium = low chlorophyll = less light absorbed for photosynthesis = less glucose = less respiration = less energy released within the plant
How does clotting occur?
Wound occurs
Platelets recruited to site
Temporary platelet plug formed
Thromboplastin --> Thrombin (done with the help of prothrobin)
Soluble fibrinogen --> Insoluble fibrin
RBC trapped in mesh
Forbs a clot
Explain how the respiratory and circulatory systems work together to supply cells with oxygen.
The respiratory system brings oxygen into the body through the lungs. Oxygen diffuses from the alveoli into the blood that was carried to the lungs from the right ventricle through the pulmonary artery. Oxygen binds to haemoglobin in red blood cells. The circulatory system then transports the oxygenated blood from the lungs back to the heart through the pulmonary vein, which is then pumped out of the heart by the Aorta. Oxygen diffuses from the blood into cells, where it is used in aerobic respiration to release energy. Carbon dioxide produced during respiration is carried by the blood back to the lungs through the vena cava, RA, RV, and Pulmonary Artery.