LEAVING CERT EXPERIMENTS BIOLOGY (DO IN ORDER)

leaving cert biology experiments

What is the use of buiret reagent in the lab

to test for protein

what is the use of benedicts solution in the lab

to test for reducing sugars

when preparing a sample of cheek cells on a microscope slide why did you

i) place a coverslip over the cells

ii) apply methylene blue to the cells

i) hold sample in place or prevent drying out

ii) to stain cells and make them easier to see

when extracting dan from a tissue why did you use

i) washing up liquid

ii) freezer cold ethanol

i) breakdown membrane

ii) to take DNA out of solution or make visible

when using seeds to investigate the effects of IAA on plant why did you

i) carry out a serial dilution of an IAA solution

ii) place the seeds on a grid in petri dishes

i) to make solutions of different concentrations of IAA

ii) to measure growth accurately

when carrying out an activity to investigate osmosis

i) why did you use visking tubing

ii) how did you know osmosis had taken place

i) to act as a selectively permeable membrane

ii)mass of tubing increased or tubing got fuller

is oxygen required for fermentation

no

where in the cell does fermentation occur

cytosol or cytoplasm

from what substance does the yeast make the alcohol/ did you use

glucose or sugar or starch

what is the optimum temperature for this fermentation process to occur in

20 to 35 degrees

how did you maintain this temperature at a constant level for the duration of fermentation

used a water bath or incubator

how did you know fermentation was finished

no more gas was released or no more bubbles

how did you test for the presence of alcohol

iodoform test

give the colour of positive result of the test for alcohol

yellow

what is meant by the term dicotyledonous

two seed leaves

what plant did you use to examine the transverse section of a dicotyledonous stem

geranium or buttercup

why is it important to use a very thin section when examining the tissues in the stem

to allow light to pass through effectively to be able to see the cells clearly

describe to steps you took to cut the stem safely (2)

used a backed blade

cut away from body (fingers)

how did you transfer the section onto the microscope slide

using tweezers or blade or forceps

name the part of the microscope you used to bring the section into sharp focus

fine focus wheel

why is it important scientists publish the results of their research

spread knowledge and peer review

how can scientists avoid bias in scientific experiments

large sample size

use of placebo

double blind testing

when carrying out certain experiments how would you ensure that reactants or organisms are maintained at a constant PH over a period of a few hours

use ph buffer

when carrying out certain experiments how would you ensure that reactants or organisms are maintained at a constant temperature over a period of a few hours

water bath or incubator

when you used yeast to prepare alcohol what other product was produced during fermentation

carbon dioxide (CO2)

what test did you use to confirm the presence of alcohol

iodoform test

when using a microscope to examine biological specimens how did you calculate the magnifying power of the microscope

multiply power of eyepiece lens by the power of the objective lens

when using a microscope to examine biological specimens how did you alter the amount of light shining on your specimen

adjust lamp

adjust diaphragm

in relation to food tests carried out on foods why should brown paper used in test for fat be aloud dry out

to ensure translucent stain is not just water

in relation to food tests carried out on foods which other food test other than fat required the application of fat

reducing sugar or benedicts

where in the cell does dark stage take place

chloroplast

why is the dark stage called the dark stage

light is not required

name the plant used for the influence of light intensity on rate of photosynthesis

Elodea/pondweed

why did you use this plant

produces bubbles as it is aquatic plant

how did you measure the rate of photosynthesis in this plant

counted number of bubbles per unit time

name a fungus other than yeast that you have studied as part of your course

rhizopus

give one way the fungus you have named differs from yeast

multicellular and has hyphae

mention two aseptic techniques you used in your investigation into the growth of leaf yeast using agar plates to ensure a pathogen free environment

minimal opening of container and when we did we opened beside open flame

soak equipment in disinfectant

what type of agar is recommended for optimal growth of yeast and other fungi

malt agar

describe how the plates were stored, from the intro of the yeast source until yeast growth became visible on the agar

right side up for first 2 days then in incubator upside down at 15-30 degrees for 2 to 7 days

how did you identify the leaf test growing on the agar

pink colonies formed

suggest a reason why few or no leaf yeast may have grown on the agar

air pollution

time of year

name of ecosystem you have studied

small woodland

give example of a possible error in ecological surveying

sample size too small

biased

quadrat size unsuitable

suggest how this error may be minimised or prevented

pen over shoulder technique to avoid areas being specifically chosen

give an example of an adaptive feature an animal may have to allow them to escape capture

leaf insect looks like leaf

explain how this adaptation could help the animal escape capture

not easily seen

suggest why ecological surveying is important

it detects changes and monitors biodiversity

describe how you carried out a quantitative survey of a plant species

we used a quadrant and threw a pen over our shoulder to determine where we would make sure our survey is unbiased and we counted all the plants in that quadrat. we recorded our results and repeated the same steps about 3 more times so we could have varied and unbiased results.

give a factor, other than PH that affects enzyme activity

temperature

explain the term optimum activity

enzyme working at its most efficient rate

name the enzyme you used in your investigation you carried into the effect of PH on the rate of enzyme activity

amylase

what is source of the enzyme named above

saliva

What is the substrate the enzyme acts on

starch

explain why changing the PH would have an effect on enzyme activity.

active site shape is altered

enzyme is denatured

how did you measure the rate of enzyme activity

measure the amount of time it takes the blue-black to disappear

what is the purpose of replicates in scientific experimentation

to ensure reliability and avoid bias

what is meant by the term hypothesis

an untested explanation of an observed phenomenon

when investigating the conditions necessary for seed germination how did you provide an oxygen free environment

we used boiling water which had been cooled and put a thin layer of oil on top of the water to avoid oxygen getting in

when investigating the conditions necessary for seed germination how did you determine germination had taken place

roots and shoots were observed

in relation to an investigation you carried out to prepare and examine with a microscope a transverse section of dicotyledonous stem;

i) how did you prepare the section

ii) why is a coverslip used.

i) cut a thin section with a backed blade

ii) to prevent cells from drying out and protect the lens

when demonstrating osmosis what did you use as a selectively permeable membrane

used visking tubing

when demonstrating osmosis what led you to conclude that osmosis had occurred

increase in mass of visking tube

when isolating DNA from plant tissue give a reason for adding salt (NaCl) to the chopped plant tissue

to clump DNA

to separate protein from DNA

when isolating DNA from plant tissue why was the picture containing the chopped plant tissue, salt and washing up liquid kept at 60 degrees for a long period of time

to denature enzymes that would destroy DNA

give two examples of limitations of the scientific method

the extent of our knowledge

accidental discovery

when testing a solution for the presence of a reducing sugar, you either used Benedicts or Fehlings test. name the control you used for this experiment

water

when testing a solution for the presence of a reducing sugar, you either used Benedicts or Fehlings test. what colour were the contents of the control tube at the end of the test

blue

during practical studies you carried out certain routine procedures. how did you add a very small volume of a solution

dropper

syringe

pipette

during practical studies you carried out certain routine procedures. how did you ensure the PH of a solution remained constant

use a PH buffer

when preparing a microscope slide of human cheek cells or other animals, how did you transfer the cells to the slide

we used a cotton bud to take the sample from the cheek then transferred it using the cotton bud onto a slide

when preparing a microscope slide of human cheek cells or other animals, how did you improve visibility of the cells on the slide

add a stain

add a coverslip

when immobilising an enzyme you used a gel substance to trap the enzyme. you also used a second substance to make the gel insoluble. name the gel you used to trap the enzyme

sodium alginate

when immobilising an enzyme you used a gel substance to trap the enzyme. you also used a second substance to make the gel insoluble. name the second substance you used to make the gel insoluble

calcium chloride

what is the pulse in relation to human

the rhythmic expanding and contracting of an artery

what makes the wrist or temple or neck a suitable part of the body to detect a pulse

artery near the surface

what was the control in the investigation on the effect of exercise on the breathing rate or pulse rate

rate measured at rest prior to beginning investigation

what was the purpose of this control

comparison with result

recovery time is the duration of the period following exercise which the breathing rate or pulse rate returns to normal. suggest how you might measure recovery time

count how long in minutes or seconds it takes for the pulse to return to normal rate as measured before

explain what is meant by the term dormancy in seeds

period during which germination does not occur

period of new growth

how does digestion contribute to successful seed germination

to make nutrients transportable to the embryo

in the investigation you carried to show the digestive activity during seed germination. state whether you carried out this investigation using starch agar or skimmed milk protein

starch agar

name a type of enzyme in the seed that carries out this digestion

amylase

why were the seeds soaked in water at the beginning of the investigation

to start up germination process

when preparing the seeds, they were also split and sterilised. why is it recommended you sterilise the seeds

to remove all microorganisms

when preparing the seeds, they were also split and sterilised. why were the seeds soaked in water at the start of the investigation

enzyme in contact with substrate

how did you know that digestive activity had occurred on one of your investigation plates

we flooded the plates with iodine solution and there was clear areas under seeds

how did you know that digestive activity had not occurred in one of you investigation plates

there was no clear areas under seeds

give a reason for what you observed when digestion had not taken place

seeds were dead.

enzyme was denatured

see first 2015 question on studyclix

contains a graph

in relation to isolation of DNA from plant tissue, explain why you used washing up liquid

to breakdown the cell membrane

in relation to isolation of DNA from plant tissue, explain why you used sodium chloride

to cause dna to clump

in relation to isolation of DNA from plant tissue, explain why you used protease

to breakdown the protein in the chromosomes

in relation to isolation of DNA from plant tissue, explain why you used freezer cold ethanol

make DNA visible

in relation to investigation carried out into heat denaturation of an enzyme;

name the enzyme you used

amylase

in relation to investigation carried out into heat denaturation of an enzyme;

name the enzymes substrate

starch

in relation to investigation carried out into heat denaturation of an enzyme;

name the products formed

maltose

in relation to investigation carried out into heat denaturation of an enzyme;

how did you denature the protein

heat to high temperature

in relation to investigation carried out into heat denaturation of an enzyme;

how did you know that the enzyme had been denatured

tested positive for starch using iodine test

in relation to investigation carried out into heat denaturation of an enzyme;

why are buffers needed when carrying out experiments with enzymes in school

to maintain constant PH