2019 Paper 1 Flashcards
How is the volume of water lost by leaves controlled
By the guard cells opening and closing stomata
Describe transport of water through plant roots to atmosphere
Water is transported in xylem. Water evaporates from leaves through stomata
Give two reasons why rate of water loss increases in a plant
If it was warmer
It was windier
Explain why a person with a leaking valve has difficulty exercising
The valve cannot stop the back flow of blood so less blood is pumped around the body.
Less oxygen is supplied to the muscles so less aerobic respiration occurs so less energy is released so less efficient muscle contraction
Anaerobic might occur instead, causing an oxygen debt. The buildup of lactic acid can cause muscle fatigue
What must someone take for the rest of their life if they have a mechanical heart replacement
Anti blood clotting drugs
—> this stops blood clots forming and as a result can also cause excessive bleeding from cuts
Describe how the small intestine is adapted for efficient absorption
Villi provide a large surface area for diffusion
Walls of vili are thin for a short diffusion distance
Small intestine is very long so their is more time for absorption
Has a good blood supply so it maintains steep concentration gradient
Cells have lots of mitochondria for aerobic respiration providing energy for active transport
Define the term double circulatory system
Deoxygenated is pumped to the lungs by right side of the heart. Oxygenated blood is pumped to the body by the left side
Explain why having only one ventricle makes circulatory sister less efficient
Oxygenated and deoxygenated blood mix so less oxygen reaches cells and tissues
Explain why an axolotl may die with a low concentration of of oxygen
Concentration gradient of oxygen is less steep so less oxygen can diffuse into gills of axolotl and it’s blood. Less aerobic respiration can occur so anaerobic occurs instead so lactic acid is produced which is toxic
Explain how pancreatic cancer can cause a person to loose weight
Reduced production of amylase enzyme.
Food is not fully digested and less glucose is absorbed into bloodstream
Less glucose available for respiration so more fat used up instead in respiration and metabolic reactions
Explain how a monoclonal antibody works to treat cancer
Bind radioactive substance to a monoclonal antibody
Monoclonal antibody will only attach to cancerous cells
Radioactive substance will bind to cancer cells and destroy them
Explain why cells loose water when a person has diabetes
The blood is more concentrated ( has less water molecules) than the solution in cells - it is dilute ( more water molecules) so water moves out of cells and into the blood by osmosis through a partially permeable membrane.
