Unit 3/6 Flashcards Preview

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Flashcards in Unit 3/6 Deck (11):

describe how the effect on the heart in daphnia can be investigated practically, and discuss whether there are ethical issues n the use of invertebrates

- caffeine is a stimulant (alcohol is a depressant and will do the opposite)
- cardiac muscle has intrinsic rhythmicity
- this cardiac rhythm is maintained by a wave of excitation which travels across the heart muscle which is generated in the heart muscle
- SAN sets up wave of excitation that travels across the atria which depolarizes the cells and causes the atria to start contacting
- wave of excitation reaches the AVN
- AVN slightly delays the wave
- AVN slightly delays the wave of depolarization
- Electrical impulse travels down the purkyne fibers in the bundle of His
- penetrates through the septum and around ventricles
- depolarization starts at the bottom so the muscles contract at the bottom first to squeeze the blood out
- stimulation of the SAN causes more waves of depolarization and shorter delay at the AVN. this causes a increase in heart rate


describe how to investigate the vitamin C content of food and drink

DCPIP is blue, but when the vitamin C (absorbic acid) is added it reduced the DCPIP to a colorless solution


describe how membrane structure can be investigated practically, e.g. by the effect of alcohol concentration or temperature on membrane permeability

- red pigment in beetroot is found in the cell vacuole surrounding the tonoplast
- pigment cannot through the membrane but can pass through cell wall if membrane is disrupted
- increased temperatures causes and increase in the kinetic energy of phospholipids in the cell membrane, thus causes gaps. the proteins also denature at high temperature, causing gaps in the membrane
- increased alcohol concentration will dissolve the dissolve the phospholipids as it is soluble in organic solvents, thus causing large holes in the membrane


describe how enzyme concentration can affect the rates of reaction and how this can be investigated practically by measuring the initial rate of reaction

- enzymes are globular proteins made of a sequence of amino acids
- they are biological catalyst which speed up reactions without being used up themselves
- their structure is important as they are folded into a unique 3D way so that they have a specific active site
- substrate will bind to active site to form enzyme-substrate complexes
- the more enzymes present, the more active sites available, this the rate of reaction increases
- substrate will become limiting factor


describe the stages of mitosis and how to prepare and stain a root tip squash in order to observe them practically

- chromosomes coil and condense
- 2 daughter chromatids attached by centromere
- nucleolus breaks down and disappears centrioles move to opposite poles, separate and form spindles
- nuclear membrane breaks down
- spindle fibers attach to centromeres
- chromatids are moved along the equator on the metaphase plate
- spindle fibers contract and shorten pulling apart the chromatids towards the opposite poles of the cell, the centromeres split to form the V shape
- this process needs energy in the form of ATP from respiration
- nucleoli, centrioles and nuclear envelope form
- chromosomes unravel and become less dense
- spindle fiber breaks down
- division of cytoplasm occurs
- in plants the membrane will separate to create two genetically identical daughter cells, in plants a cellulose wall builds up to create two separate cells


describe how totipotency can be demonstrated practically using pant tissue culture techniques

- stem cells - undifferentiated cells that have the potential to develop into many different types of specialized cells as their genome contains all/most genes
- totipotent - an undifferentiated cell which can differentiate into any specialized cell
- pluripotent - an undifferentiated cell which can differentiate into any specialized cell apart from embryonic cells
- multipotent - undifferentiated cell which can differentiate into several related cells


describe how to determine the tensile strength of plant fibers practically

- this gives the cell it's regular shape and gives it strength and support so it will not burst in solution with high water potential
- made from insoluble cellulose, microfibrils and hemicellulose
- if strengthened with Suberin or lignin, the cell wall permeability increases so water can no longer pass through
- first layer to form when plant cell divides
- made of pectin and polysaccharides which act like glue to hold the neighboring cells together
- pectin forms with calcium ions to make calcium pectate
- made of long chains of beta glucose joined together by 1,-4 glycosidic bonds (polysaccharide)
- each alternate group is inverted as this allows hydrogen bonds
- the chains are straight and unbranched so are able to be cross linked
- group of cellulose molecules bound together with hydrogen bonds form microfibrils
- group of cellulose molecules bound together through hydrogen bonds
- form helical arrangements and bind with other polysaccharides to form hemicellulose


describe how to investigate plant mineral deficiencies practically

- nitrate ions are used to make amino acids, these are subsequently used to make proteins
- proteins are used for structures in plant to build biomass and allow growth to occur
- enzymes are proteins, thus nitrates are needed for enzymes, without enzymes the metabolic reactions of the cell would stop
- older leaves turn yellow and die, growth is stunted
- calcium ions are used in middle lamella of plant cells which combines with the pectate to form the calcium pectate which holds the cells together
- these play a role on the permeability of the cell membrane
- growing points die back and young leaves turn wrinkled and yellow
- these are needed to produce the green pigment chlorophyll, thus are needed to photosynthesis to occur
- yellow areas develop in older leaves and growth slow
- phosphate ions are needed for the phosphate groups in ATP and ADP, these are needed to store and transfer energy in the cell
- needed to synthesis nucleic acids
- green leaves with dark purple veins observed


describe how DNA can be amplified using the polymerase chain reaction (PCR)

- heat stable DNA polymerase must be used
- optimum temperature of 72 degrees
- needs to bind to primer to begin synthesis


describe how to investigate the effect of different antibiotics on bacteria

there are two different types of antibiotic
- bacteriostatic - completely inhibits growth of the microorganism
- bacteriocidal - kills bacteria by inhibiting enzymes which produce the cell wall and breaking the cell wall down

characteristics of bacterial cells:
- prokaryotic
- cell wall - peptidoglycan
- no mitochondria - respiration occurs in mesosome
- slime capsule
- genetic material is a nucleotide, with plasmids present too


describe how to investigate the effects of exercise on tidal volume and breathing rate using data from the spirometer traces

- the ventilation center is located inn the medulla oblongata and involves the negative feedback system during breathing
- impulses from the ventilation center which travels along