Unit 3/6 Flashcards

(11 cards)

1
Q

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

A
  • 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
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2
Q

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

A

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

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3
Q

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

A
  • 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
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4
Q

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

A
  • 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
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5
Q

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

A

PROHAPSE
- chromosomes coil and condense
- 2 daughter chromatids attached by centromere
- nucleolus breaks down and disappears centrioles move to opposite poles, separate and form spindles
METAPHASE
- nuclear membrane breaks down
- spindle fibers attach to centromeres
- chromatids are moved along the equator on the metaphase plate
ANAPHASE
- 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
TELOPHASE
- nucleoli, centrioles and nuclear envelope form
- chromosomes unravel and become less dense
- spindle fiber breaks down
CYTOKINESIS
- 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

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6
Q

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

A
  • 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
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7
Q

describe how to determine the tensile strength of plant fibers practically

A

CELL WALL:
- 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
MIDDLE LAMELLA:
- 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
CELLULOSE:
- 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
MICROFIBRIL:
- group of cellulose molecules bound together through hydrogen bonds
- form helical arrangements and bind with other polysaccharides to form hemicellulose

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8
Q

describe how to investigate plant mineral deficiencies practically

A

NITRATES:
- 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
DEFICIENCY:
- older leaves turn yellow and die, growth is stunted
CALCIUM:
- 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
DEFICIENCY:
- growing points die back and young leaves turn wrinkled and yellow
MAGNESIUM:
- these are needed to produce the green pigment chlorophyll, thus are needed to photosynthesis to occur
DEFICIENCY:
- yellow areas develop in older leaves and growth slow
PHOSPHATE:
- 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
DEFICIENCY:
- green leaves with dark purple veins observed

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9
Q

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

A
  • heat stable DNA polymerase must be used
  • optimum temperature of 72 degrees
  • needs to bind to primer to begin synthesis
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10
Q

describe how to investigate the effect of different antibiotics on bacteria

A

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
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11
Q

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

A
  • 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
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