🐶Mission X Flashcards
ref to back of book for unFC Q (63 cards)
With reference to the cohesive and adhesive properties of water, suggest and explain how the formation of small clumps of soil helps to maintain the soil water around the root tip.
Water molecules form hydrogen bonds which creates cohesion between water molecules. The water molecules adhere to the soil clumps. Clumps provide small places in which water collects.
State the term used to describe enzymes that act outside the cells that synthesise them.
extracellular enzymes
Explain what is meant by a polysaccharide.
More than two monosaccharides joined by glycosidic bonds. Eg: sucrose.
In liver cells, enzymes are attached to the membrane of smooth endoplasmic reticulum.
With reference to the functions of smooth endoplasmic reticulum, suggest the advantages of having enzymes attached to the membrane rather than free in the lumen.
- There is more efficient synthesis of products such as lipids (Eg: cholesterol), and steroid hormones such as oestrogen and testosterone.
(synthesis of products require more than one enzyme)
- The membrane gives the enzymes greater protection against degradation.
Explain the advantages of using a transmission electron microscope compared with a light
microscope when viewing a liver cell.
It has a higher resolution (of 5nm compared to 200nm) and so higher magnification without loss of detail. Organelles such as ribosomes are visible.
Explain why this protein is described as globular.
This protein is spherical and soluble. Amino acids with hydrophilic R groups are on the outside of the molecule. Hydrophobic R groups in the centre. Has a physiological role. (Is an enzyme)
State the function of carbonic anhydrase in red blood cells.
Carbonic anhydrase catalyses the reaction between water and carbon dioxide to form carbonic acid.
Different strains of a virus have been formed by mutation. In each strain, the primary structure of the active site of the enzyme (which allows the virus to leave host cells) remains unchanged.
Suggest why the primary structure of the active site remains unchanged in each strain of the influenza virus.
The substrate is able to bind to the active site, so viruses can leave host cells to infect other cells.
The gene mutation is not occuring in the gene coding for the amino acids in the active site for the enzyme. The gene for the enzyme is essential for survival.
State the differences between the structure of a virosome and a virus
Virosome has no genetic material or a protein coat.
(Of a plant cell) Enzymes contained in the vacuole are released into the cytoplasm.
Name an organelle found in animal cells that has a similar function to the vacuole in the developing xylem vessel elements.
Lysosome
During development of the xylem vessel elements the pH of the cytoplasm decreases.
This change in pH activates enzymes in the cytoplasm that cause organelles to swell.
Suggest how a change in pH of the cytoplasm can activate enzymes.
Active site becomes complementary to substrate, because hydrogen/ionic bonds altered between R groups of amino acids.
State one role of cholesterol in phospholipid bilayers.
Cholesterol in phospholipid bilayers maintains the fluidity of the membrane. (Eg: Reducing fluidity at high temperatures).
It maintains the stability of the membrane. Without cholesterol, membranes would easily rupture. Its flat ring structure interferes with the movement of fatty acid tails and reduces the lateral movement of phospholipids.
It prevents the entry of hydrophilic substances.
Explain why sodium ions cannot cross phospholipid bilayers by simple diffusion.
Sodium ions are positively charged and so are repelled by the hydrophylic tails.
No. 3 Number circled blue (need to ask about ms)
Compare facilitated diffusion and active transport by stating ways in which they are different.
Both involve a transport protein,
No 3 Number circle blue
Compare facilitated diffusion and active transport by stating ways in which they are similar.
Suggest an advantage for this reaction pathway occurring in the smooth endoplasmic reticulum of a cell rather than in the cytoplasm.
phospholipid–>arachidonic acid with enzyme, COX–>prostagladin (small lipids formed from phospholipids)
SER is membrane-bound and so can provide the arachidonic acid/phospholipids. The reaction is separated from the cytoplasm, so the cell chemistry is not disturbed.
SER is involved in lipid transport: prostaglandins are lipids therefore they can be transported from the SER or stored in the SER.
Suggest how modifying the R-group of an amino acid in the COX enzyme can reduce the catalytic activity of the enzyme.
The shape of the active site is changed, so the active site is no longer complementary to the substrate. The enzyme-substrate complex could be formed at a reduced rate or not at all.
Outline the role of the tissue that the endodermis is found.
The endodermal tissue stops water moving through the apoplast, so that water moves from the cell wall to the cytoplasm. It controls the substances into the root’s stele.
State an example of an organic compound that is translocated in the root of an iris.
Sucrose, amino acids and auxin.
Name four polysaccharides.
Glycogen, cellulose, amylose and amylopectin.
What specific monomers are the four polysaccharides made up of?
They are all made up of alpha-glucose, except cellulose which is made up of beta-glucose.
Discuss the glycosidic bonds of the four polysaccharides.
Amylose and cellulose have 1,4 bonds. Glycogen and amylopectin have 1,4 and 1,6 bonds.
What is the function of amylopectin and amylose?
Energy storage in plants
What is the function of glycogen?
Energy storage in animals
