Alevel Flashcards
Plant growth requires the production of new xylem cells.
Describe how new xylem cells are produced.
produced in meristems by differentiation of the stem cells
Suggest why Hydra plant reproduces asexually when conditions are favourable.
offspring produced can be produced rapidly in large number and all have same adaptations
Suggest and explain adaptation that is likely to be present in these sperm cells.
acrosome to penetrate the egg
lots of mitochondria for energy
Show the main differences in structure between glucose and starch.
Glucose -
monomer
monosaccharide
no glycosidic bond
Starch -
polymer
polysaccharide
glycosidic bond
Carbohydrates contain only the elements carbon, hydrogen and oxygen.
Polypeptides contain carbon, hydrogen, oxygen and nitrogen.
Name one other element present in polypeptides.
Sulfur
Creatine kinase (CK) is an enzyme that catalyses reactions in heart muscle.
Suggest why high levels of CK in the blood indicate that a person may have had a heart attack.
creatine kinase is an intracellular enzyme, presence in blood indicates damage to the heart
Explain why the oncotic pressure of the blood depends only on the concentration of large plasma proteins.
large plasma proteins cannot pass through capillary wall
Explain blood glucose levels (negative feedback loops)
When blood glucose levels are high, beta cells detect, and insulin is produced so that it can turn glucose into glycogen to be stored for later.
When blood glucose levels are low, alpha detect, and glucagon is produced so that glycogen can turn into glucose by the liver
What is the final electron acceptor in the light dependent stage of photosynthesis
NADP
Suggest and explain the function of DCPIP in photosynthesis practicals
DCPIP acts as the final electron acceptor instead of NADP
Describe how new xylem cells are produced
Produced in meristems by differentiation
When doing a potometer practical, what precaution is needed
Ensure screw clip is closed to prevent entry of water whilst measuring
Cut shoot slanted to ensure continuous column of water
Explain why the oncotic pressure of the blood depends only on the concentration of large plasma proteins
Too large to fit through the pores so left in the blood
Imbalance of large plasma protein between blood and tissue fluid results in oncotic pressure.
What is the most important process in determining the overall body plan of an organism
Mitosis
Define species richness
The number of species in an area
Explain why some regions of DNA can be described as non coding
Not present in the mature mRNA and cannot be translated
Evaluate the treatments for type 1 diabetes that have been used in the past as well as current and potential future treatments (6)
In the past insulin was gained from animal pancreas, and this was advantageous as it kept people alive however there was a high production cost and ethical issues as animal products were involved.
Currently, genetically modified bacteria is used. It is much purer, overcomes ethical issues, has a lower production cost and is easier to use. However side effects can occur, and the routine is difficult to understand at first - not user friendly.
Potential future treatments, is transplants of pancreas this means no need for insulin injections, and improved quality of life however it is initially a high cost and needs a donor which can take a long time.
Explain how glucose produced in photosynthesis is translocated to parts of the plant where glucose is metabolised or stored. (6)
Phloem loading -
Glucose is converted to sucrose
Mass flow - The pressure difference causes mass flow where sucrose moves from source to sink
Phloem unloading.
Diffusion of sucrose
sucrose is converted back to glucose
What is cofactor for carbonic anhydrase
Zn 2+
Name and define two other levels of biodiversity
Habitat biodiversity - number of different habitats
Species biodiversity - richness and evenness of a species
Describe how oncotic pressure is established
Plasma proteins are too large to leave the capillary
creates a low water potential in the capillary
water moves by osmosis down the water potential gradient into capillary
Explain the role of meristem tissue in a stem.
Source of undifferentiated cells for growth
Can differentiate into other cells
Name one potential use of stem cells in medicine
Medical research
Repair of damaged tissue
explains why plants need a vascular system to support amino acid synthesis
To transport nitrates to the leaves using xylem tissue
Outline how ATP is produced in mitochondria by chemoiosomosis
H+ ions flow down a concentration gradient from inter membrane space to matrix
Energy provided to join ADP and Pi to form ATP
