Module 2 - Biology Flashcards
DNA sequence in genes code for polypeptide molecules such as pepsin and titin.
Explain why a process known as transcription is necessary for polypeptide synthesis.
Transcription is necessary for polypeptide synthesis because the gene is copied to the mRNA. And the RNA goes to the ribosomes for polypeptide synthesis as the DNA is too large to fit through the nuclear pores.
Titin is a fibrous protein. Pepsin is a globular protein. Compare the properties and functions of fibrous proteins and globular proteins in the human body.
Fibrous protein are insoluble, elongated strands, strong and flexible. They are used for things like protection, e.g. keratin in skin, hair and nails.
Globular protein is soluble, spherical in shape and a tertiary structure.
It is used to package DNA, and transport substances in blood. e.g haemoglobin in RBC carry oxygen.
State the role of a gene
It codes for one or more polypeptide
Explain how the structure of DNA allows replication
DNA is double stranded and both strands act as templates.
The hydrogen bonds between the complementary base pairings can easily be broken allowing replication to occur.
However the hydrogen bonding between A&T and C&G are different.
There are 3 H bonds in C&G and 2 H bonds between A&T.
Explain why phenolphthalein indicator was able to detect the breakdown of triglycerides.
When triglycerides breakdown they form fatty acids. More breakdown means the pH falls which the indicator can detect.
What is a triglyceride
Triglyceride is made up of a glycerol and 3 fatty acids.
It usually has a high ratio of Hydrogen to Oxygen
Explain how the structure of phospholipids allow them to form the bilayer of a plasma membrane
Phospholipids have a hydrophobic tail and hydrophilic heads. The hydrophilic heads form H bonds with the water and the hydrophobic tails face towards each other.
What is the structure of an amino acid.
Central Carbon attached to Carboxyl group (COOH) , Amino group (NH2) and side chain (R)
Orlistat is a drug that directly reduces the breakdown of fat in the small intestine. This reduction in breakdown leads to less fat being absorbed into the body.
Suggest the mechanism by which orlistat reduces the breakdown of fat.
Enzyme Inhibitor
Define the term balanced diet
Balance diet means consuming nutrients in the correct proportions
Suggest and explain why over consumption of milk and beef can lead to malnutrition.
Milk and beef are both triglycerides and both contain large amounts of energy, more than what a human needs.
Over consumption increases fat storage which in turn leads to obesity and other health conditions.
Eating lots of dairy and meat could also mean the diet is not balanced anymore.
What are purines and pyrimidines.
Purines have 2 carbon rings - Adenine and Guanine
Pyrimidines have a carbon ring - Cytosine and Thymine
DNA carries the genetic code which is non overlapping and degenerate.
What does non overlapping and degenerate code mean?
Each nucleotide is only part of one triplet of bases and more than one triplet codes for a amino acid.
What is the correct definition of the term coenzyme?
A non protein organic molecule, not permanently attached to an enzyme but needed to allow the enzyme to function
Explain why onion root tips are used to view cells undergoing mitosis.
It is where the cells are able to divide , as it is a meristem, and no chloroplasts are present.
Suggest a stain that a student can use to highlight the nuclei of cells during mitosis
Methylene blue
Carl Woese suggested a new top level taxon - domain.
He used his results from studying RNA
Name the cell component that appears in organisms of all 3 domains that Woese suggested.
Ribosomes
One of the domains is called Eukarya.
Name the other 2 domains
Bacteria
Archaea
State 2 defining features of all members of the domain Eukarya
Nucleus
Linear DNA
80s ribosomes
Which stage in the cell cycle is DNA polymerase most active
S phase
Describe the function of DNA polymerase
Make phosphodiester bonds between adjacent nucleotides.
What is the oder of increasing complexity of organisation within an organism?
Cell –> Tissue –> Organ –> Organ System
What elements are found in proteins?
Carbon, Hydrogen, Oxygen. Nitrogen, Sulphur
Human pancreatic lipase breaks the bonds between fatty acids and glycerol.
What name is given to this reaction>
Hydrolysis
A zygote undergoes rapid cell division.
Explain why the type of nuclear division in a zygote is mitosis and not meiosis.
Mitosis is used for the growth of a zygote where it needs to have identical genetic information.
Explain the role of embryonic stem cells in the development of the embryo.
Embryonic stem cells are undifferentiated cells, they can differentiate into anything and become specialised in its particular function - developing the foetus.
A blastula is an animal embryo at an early stage of development. As the blastula develops, it becomes a hollow ball of cells with an inner cell mass; which is a source of embryonic stem cells.
Explain why the cells of the inner cell mass are not totipotent stem cells.
They are not totipotent because they cannot form whole organisms. They cannot form some tissues such as the placenta
Blastula are pluripotent
Collagen molecule has 3 polypeptide chain each with 1050 amino acids, wrapped into a triple helix.
Describe and explain why collagen is a fibrous protein.
Collagen is a fibrous protein because it is a long chain of amino acids.. It is strong and flexible and it is insoluble. It has a structural function to provide strength.
Suggest why collagen is such a strong molecule
There are many hydrogen bonds between the polypeptides
There are crosslinks between collagen molecules
What happens in a RER
Translation of some proteins takes place in a eukaryotic cell
Describe the structure of the rough endoplasmic reticulum
It has a phospholipid bilayer and there are a network of membranes enclosing a fluid filled space. The surface is covered with ribosomes.
Explain the role of the membrane in the RER
Compartmentalisation and separates synthesised proteins from the cell cytoplasm
Explain how the nucleotides in a DNA molecules are arranged as two polynucleotide strands.
DNA molecules are made up of nucleotides. These are held together by phosphodiester bonds.
There are hydrogen bonds between the complementary bases. 2 hydrogen bonds between A and T and 3 hydrogen bonds between C and G.
Two antiparallel (running in opposite directions) polynucleotide strands twist to form the DNA double-helix.
Name 2 enzymes involved in DNA replication
helicase - separating
DNA ligase - joining
Explain why enzymes are essential to all organisms.
Enzymes are biological catalyst which speed up the reaction and lowers the activation energy so reactions can take place at low temperatures.
what is a protoctist
An eukaryotic organism
It has a nucleus but no cell wall
State 3 changes that the student would need to ensure to do / improve when doing a biological drawing.
The label lines should not cross
There should be no arrowheads
No shading or colouring
Both a TEM and a SEM can be used to view the same cell. However, the images formed will be different.
Compare the resolutions of these microscopes and the images formed by them. [4]
TEM has a higher resolution between 0.05 and 2nm. It shows the cells organelles such as the nucleus and the mitochondria.
SEM has a lower resolution between 5 - 50nm and it shows the surface of the cell rather than the organelles. However it does provide a 3D image.
Where are erythrocytes and neutrophils formed?
In the bone marrow
What is one of the places ciliated epithelial cells are found in?
Trachea
The cell wall of the guard cell is thicker or thinner on the side furthest away from the stoma?
Thinner
Erythrocytes and neutrophils are both examples of specialised blood cells.
Squamous and ciliated epithelial cells are also examples of specialised cells.
Describe how each of these four cells is specialised for its function. [6]
Erythrocytes are red blood cells. They are specialised because they have no nucleus and have biconcave discs to increase the surface area to volume ratio. This means they can carry more oxygen to transport around the body. In addition they are flexible, meaning they can fit through narrow gaps of the capillary tubes.
Neutrophils are white blood cells. They have a multilobed nucleus making it easier for them to squeeze through small gaps to get to the site of infections. The granular cytoplasm contains main lysosomes that contain enzymes used to attack pathogens.
Squamous epithelial cells are very thin and one cell thick, therefore rapid diffusion can occur and exchange of gases at the alveoli
Ciliated epithelial cells have cilia which move in rhythm to move mucus and trapped pathogens.
Suggest why goblet cells have large number of mitochondria.
They provide a lot of energy
Suggest how the role of the Golgi apparatus is relevant to the function of the goblet cell.
The Golgi apparatus packages protein and aids secreting the mucus in exocytosis
Sjogren’s syndrome is a rare condition that can reduce the production of mucus.
Suggest how the upper respiratory tract of a place with Sjogren’s syndrome might be affected.
More infections leading to coughing
How are two amino acids joined together
Peptide bonds
The process of esterification leads to the formation of ester bonds during the production of triglycerides.
Describe what is meant by the term esterification
The reaction between carboxylic acid and alcohol. It is a condensation reaction and removed H20
Explain the meaning of the phrase semi conservative replication
Semi conservative replication is when each strand of DNA acts as a template strand for a new double helix
DNA ligase is one enzyme involved in the replication of DNA
State 2 other enzymes involved and describe their functions
DNA helicase unzips the DNA molecules by breaking the hydrogen bonds and separating the 2 strands
DNA polymerase forms phosphodiester bonds forming the sugar phosphate backbone
Give one way that an image produced by a laser scanning confocal microscope differs from that produced by an electron microscope
Laser scanning confocal has a Lower resolution compared to electron microscope
It also allows live species to be viewed
Uses fluorescent tags
The use of stem cells is being evaluated for the treatment of certain human diseases
Name 2 potential sources of human stem cells and for one source, describe an ethical issue associated with the use of stem cells.
Embryonic and bone marrow. The ethical issue with use embryonic sources is that embryos die, some may believe that lives are being killed
What observations are made at prophase
In prophase chromosomes are condensed
Nucleolus is not visible
In meiosis, metaphase 1 occurs
Explain how the organisation of homologous chromosomes during metaphase 1 increases genetic variation
The organisation of homologous chromosomes increases genetic variation because there is random assortment
The homologous chromosomes line up on the equator and one of the homologous pair end up facing either pole.
Causing each chromosome to be genetically different
Glucose is a biological molecule required by cells for cellular respiration
State the physical property of glucose that allows it to be easily transported in the bloodstream
Glucose is soluble in water
Multicellular organisms need to be able to convert monosaccharides into polysaccharides and back again
Mammals convert the monosaccharide glucose into a highly branched polysaccharide called glycogen, which gets stored in liver cells.
Explain why mammals store glycogen instead of glucose.
Glycogen is compact and can be stored in a small space
It can store lots of energy
It is insoluble so has no effect water potential of cell
Humans use the enzyme alpha - amylase to break down polysaccharides in food for absorption into the blood.
The gene is transcribed in the nucleus and translation occurs on the rough endoplasmic reticulum in cells of the salivary gland.
Describe how the molecule is prepared and secreted by cells of the salivary gland after translation has taken place.
Modification occurs at the Golgi apparatus
It is packaged into secretory vesicle and this moves along the cytoskeleton
The vesicle fuses with the cell surface membrane
Secretion occurs through exocytosis
Plasma membrane are partially permeable
One molecule that crosses membranes easily is the steroid hormone progesterone which is produced in the ovaries from cholesterol
Explain why progesterone can move across membranes
Progesterone is hydrophobic so diffuses through the phospholipid bilayer
ATP is made up of phosphate groups and 2 other molecules
Name 2 other molecules
Ribose
Adenine
Explain what standard deviation shows
Standard deviation shows spread of data around the mean
A polypeptide chain of amino acids is made. What is the bond between each amino acid and what reaction does it undergo
Peptide bond
Condensation reaction
What is the formula for Rf
Distance from origin to spot / distance from origin to solvent front
A cytoskeleton is present in all eukaryotic cells.
State how the cytoskeleton moves organelles around the cell.
Cytoskeleton uses microtubules to move organelles around the cell
Epithelial cells in the airways of mammals play an essential role in defences against pathogens
Explain the function of epithelial cells in the airways of mammals in the defence against pathogens and suggest the importance of the cytoskeleton in carrying out this function
Epithelial cells contain goblet cells which produce mucus that can trap pathogens. Then the cilia, hair like structures, move the mucus with the trapped pathogens away.
The cytoskeleton is important in this process as it makes up the cilia
Copper (II) ions act as irreversible non competitive inhibitor of the enzyme catalase.
Describe how a non competitive inhibitor works to inhibit the activity of an enzyme
Non competitive inhibitor binds to the allosteric site.
This causes the active site to change shape
Therefore the enzyme substrate complex cannot be formed
What bond holds the alpha glucose and the fructose together.
1,6 glycosidic bond
What will not effect the rate of phosphodiester bond formation
Length of DNA molecule
In human cells, the tumor suppressor gene codes for a protein that interrupts the cell cycle and prevents the copying of damaged DNA.
Which stage could this gene interrupt
G1 phase
Outline the properties of water which make it an ideal habitat for an amphibian
It is a good solvent
Ice is less dense than water
It has high specific heat capacity
The student investigates the effect of cell size on the rate of diffusion using two agar cubes and phenolphthalein indicator.
State 2 ways they can ensure their results are confident
Repeat the practical
Calculate a mean
Pick out any anomalies
Explain why the surface area to volume ratio of an organism determines whether it needs a circulatory system
Larger organisms have a smaller SA to volume ratio, therefore diffusion is slower as it has to travel longer distances
So metabolic demands are higher and nutrient supply is slower
therefore it needs a circulatory system
Living organisms have many uses for triglycerides, one of which is the production of phospholipids
Name 3 other functions of triglycerides in living organisms
Thermal insulation
Electrical Insulation
Energy storage
As the number of hydrogen decreases in methyl esters, the melting point decreases. Why is this?
There is a more kinked chain.
Less hydrogen bonds
Explain how the fatty acids in phospholipids allow the formation of membranes
Fatty acids are hydrophobic so the tails point inwards forming a phospholipid bilayer where the head points outwards.
Suggest why cell T and the cells surrounding it, can be classified as parenchyma tissue.
The cells are working together with similar functions
What are the 2 similarities and differences between the DNA nucleotide and a molecule of ATP.
DNA and ATP both have adenine base and pentose sugar
ATP has 3 phosphate groups, DNA has 1
ATP has ribose sugar, DNA has deoxyribose sugar
Explain the Benedicts test for reducing sugar
Add Benedicts Reagent (blue) to sample Heat using water bath If positive coloured precipitate Blue -- Green -- Yellow -- Orange -- Red Higher conc, further colour change
Explain the Benedicts test for non reducing sugar
Add dilute HCL To neutralise add sodium hydrogen carbonate Carry out reducing sugars test Positive then non reducing present Negative then stay blue
Explain the Iodine test for Starch
Add iodine dissolved in potassium iodide solution
Starch present then brown-orange to blue black
Starch not present then stays brown-orange
Explain the Biuret test in Protein
Add NaOH solution to make alkaline
Add Copper(II) sulphate solution
Protein present then turns purple
Protein not present then stays blue
Explain the Emulsion test for lipids
Shake test substance with ethanol
Pour solution into water
Lipid present - solution will turn milky
Lipid not present - solution will stay clear.
State the level of taxonomic group after Animal Kingdom
Phylum
Class
Order
Family
State 3 reasons why the three-domain classification system is now used in preference to the five-kingdom system.
The 3 domains fit phylogeny better.
There are differences between bacteria and archaea such as having different cell membranes
Eukaryotes all have a nucleus.
In the past roe deer’s main natural predator in Britain was a large carnivore of the cat family. The lynx became extinct in Britain around 1000 years ago
Plans are being considered to reintroduce the Eurasian lynx from these European populations to the wild parts of Britain to improve biodiversity.
Suggest one reason why some people might object to this reintroduction
Could cause potential danger to local wildlife and the environment may no longer be suitable for lynx
The Iberian lynx and Eurasian lynx were once classified within the species, based on their observable features.
In the last 10 years, the Iberian lynx has been reclassified as a separate species within the genus Lynx, on the basis of its phylogeny.
Define the term phylogeny and explain how phylogeny is related to classification. Use the lynx species as examples.
Phylogeny is the evolutionary relationship between species.
Phylogeny is the basis of classification, species within the same group have common ancestor.
The lynx are similar as they have been placed in the same genus.
Woese carried out a detailed study of RNA molecules in order to draw his conclusions.
Suggest two ways in which the scientific community are likely to have validated Woese’s research
Peer review
replication of work by others to see if same results are obtained
The Titicaca water frog, Telmatobius culeus, is an aquatic amphibian found in Lake Titcaca in South America
Name the genus of the Titicaca water frog
Telmatobius
Suggest why it is only in the last 10 years that the Iberian lynx has been classified as a separate species
Better technology has evolved
More genetic evidence
Discuss the classification of slime moulds and include the range of evidence which this classification might be based on
Slime moulds are eukaryotes. This is based on the amino acid sequences.
Amino acid sequence of slime moulds are more similar to plants and fungi than protoctists.
A conjugated protein is held together by many different types of bond.
Which bond is not formed when a conjugated protein folds into its quaternary structure
Peptide
Outline the method of chromatography that will separate the main amino acids in collagen
Breakdown the collagen into amino acids
Draw a pencil line close to the end of paper
Place sample on chromatography plate (spot on the line)
Place this into solvent
Dry and repeat
A multicellular organism with a cell wall is what kingdom and what would the cell wall be made out of.
Plant kingdom
Cellulose
A unicellular organism with a cell wall is what kingdom and what would the cell wall be made out of.
Fungi
Chitin
Describe how the genetic material is arranged in organisms in the same kingdom as a unicellular organism
Only one chromosome
In mammals the lungs act as the gas exchange system. Various components of this system work together to ensure gas exchange is efficient. Two such components are cartilage and elastic fibres.
State the roles of these 2 components in mammalian gas exchange.
Cartilage - Supports trachea
Elastic fibres - recoil of alveoli
What equipment do you use to test the thickness of the exchange surface upon diffusion
Only use one temperature
Use 2 layers of dialysis tubing
How is DNA extracted
Grind a sample to break down cell wall Mix sample with detergent to break down cell membrane Add salt - breaks H bonds Add protease - breaks down protein Add a layer of alcohol (ethanol) on top DNA sample will start forming
what type of disease of malaria
It is parasitic
Suggest how the plasma membrane of D. Discoideum is adapted for cell communication
The plasma membrane contain glycolipids
State the correct term for the definition:
The detailed structure of cells visible only with an electron microscope
Ultrastructure
Why is the second division of meiosis different from mitosis
the separating chromatids of a pair are not the same.
The walls of blood vessels contain a polymer called collagen.
Name the type of monomer from which collagen is made and explain how two such monomers are joined together.
The monomer is amino acid, they are joined together by peptide bond
The rate of movement of molecules from the plasma membrane towards the centre of living cells is often greater than that seen in the procedure the student carried out even if the cells are kept at the same temperature.
Suggest a reason for this observation.
The molecules are moved by cytoskeleton and vesicles
describes one specialisation of a sperm cell
acrosome contains enzymes to digest outer portion of egg
Explain why glucose cannot pass through a cell membrane by simple diffusion.
The phospholipids act as a barrier
Glucose molecules are too large
the binding site changes shape to fit more closely around the substrate molecule. What theory is this
Induced fit
Suggest why it is beneficial to the plant for the carbohydrate to be transferred throughout the plant in the form of sucrose rather than as an alternative carbohydrate.
sucrose is soluble so can be transported in sap, it is metabolically inactive
A student mixed an unknown substance with water and ethanol. A white suspension formed in the tube.
What is this
A lipid is formed
Discuss the benefits of using stains when making slides for light microscopy.
contrast is higher, more internal structures visible
DNA replication and transcription are two processes that occur in the nucleus of eukaryotic cells.
* Compare DNA replication and transcription by describing the similarities and differences between the two processes.
(6)
Similarities is that DNA unwinds and unzips with the help of helicase enzyme.
Both have complementary base pairings, of A-T, C-G held together by hydrogen bonds.
Differences is that only a small section of DNA (where the gene is located) unzips during transcription, whereas both strands act as templates in replication.
Products are two new daughter strands of DNA in replication and one mRNA strand in transcription.
What two substances are required to break the glycosidic bond in lactose?
Water
Lactase enzyme
State the name given to any inorganic ion that increases the activity of an enzyme.
Cofactor
A vet is concerned that a llama is unwell. The vet suspects there may be haemoglobin in the urine of the llama.
Explain how the vet could confirm this suspicion.
add biuret solution to urine)
observe colour change from blue to purple if protein is present
DNA is one of many substances which will dissolve in water. Explain why water is a good solvent.
molecules are polar
Polarity enables water molecules to attract solutes
A student tried to extract some DNA from a crushed banana at home. DNA dissolves in water but the student realised that they needed to add something to break open the nuclear envelope to release the DNA.
Suggest a suitable substance the student could use to release the DNA, and explain why it should work.
Detergent
works as an emulsifier and will break up the plasma membranes
Suggest three ways in which the use of embryonic stem cells in research has practical benefits to biological knowledge.
test how effective new medicinal drugs are
test for side effects of new drugs
for developmental research
State the name of the monomer in cellulose.
Beta glucose
What does a t test do ?
Compares two means
Stem cells can specialise to form a variety of cell types.
What other feature is shown by stem cells but not by specialised cells?
Ability to divide
compare the differences in structure between amylose and cellulose
amylose is coiled, cellulose is uncoiled
amylose is alpha glucose, cellulose is beta glucose
amylose is granular, cellulose is fibrous
Which properties of cellulose make it suitable for forming cell walls?
Strong
hydrogen bonds can be formed between adjacent fibrils
Why is the ability of water to act as a solvent important for the survival of organisms?
transport medium for reactions
Explain why plants are more able to form natural reproductive clones than animals.
most plant cells retain ability to differentiate / totipotent;
plants have, meristems
Name the enzyme that can be used to convert mRNA to single-stranded DNA.
reverse transcriptase
Explain how helper T cells act to speed up these processes
helper T cells stimulated by antigen-presenting cells
release interleukins which stimulate B cell for clonal expansion
Name one structure present in animal cells that is not present in plant cells.
Centriole
The cytoskeleton in cells consists of microtubules and microfilaments.
Describe the roles of the cytoskeleton.
Cytoskeleton maintains shape of the cell
helps movement of cilia
helps with movement of chromosomes
Plant and animal cells have different structural features.
The pancreas is an organ that secretes protease enzymes.
Outline how the organelles in pancreatic cells work together to produce and release these protein molecules from the cells
The nucleus contains the gene of the protein and produces mRNA.
The RNA leaves the nuclear pores and goes to the ribosomes for protein synthesis as DNA is too large to fit
The vesicles then transport the protein
The Golgi apparatus helps modifies and repackages the protein
the vesicle is transported along the cytoskeleton to the cell surface membrane where it fuses and is ready for exocytosis.
What two substances are required to break the glycosidic bond in lactose?
Water and lactase enzyme
Each gill is supported by a gill arch made of bone. Bone tissue is made of living cells, collagen and an inorganic component.
Explain why bone is described as a tissue and gills are described as organs.
tissues have one or few types of cell and perform one/few functions which is what a bone does
A gill is an organ because it consists of several tissues
State the term used to describe an ion that is essential for the enzyme to function.
Cofactor
Name another conjugated protein that contains a haem group.
Haemoglobin
