AS Biology Biochemistry and Cell Structure

Frage	Antworten
With reference to carbohydrates explain the difference between a CONDENSATION reaction and HYDROLYSIS	Condensation - when two monosaccharides join to form a disaccharide with the elimination of water and the formation of a glycosidic bond Hydrolysis - the addition of water to a disaccharide resulting in the formation of two monosaccharides
State whether these carbohydrates are mono-, di- or polysaccharides and give each their role in living organisms. State whether each occurs in plants, animals or both: lactose, cellulose, glucose, glycogen	Lactose - di - plants - animals - energy Cellulose - poly - plants - structure Glucose - mono - plants - animals - energy Glycogen - poly - animals - energy store
What is are ISOMERS?	Compounds that have the same chemical formula but which differ in the arrangement of the atoms
What does POLAR mean?	Molecules that have two ends or poles that interact differently with water and fat. A hydrophilic head is attracted to water but not to fat, whereas a hydrophobic tail mixes readily with fat but is repelled by water
Name the products formed and the type of bond that is broken when a triglyceride is broken down	Broken down to form one molecule of glycerol and three molecules of fatty acid with the elimination of water and the breaking of an ester bond
Suggest why parts of organisms that move, such as seeds, use lipids as an energy store rather than crabohydrates	When oxidised, lipids provide more than twice as much energy as carbohydrates. If fat is stored, the same amount of energy can be provided for less than half the mass. It is therefore a lighter storage product
What is meant by metabolic water?	Water produced from the oxidation of food is called metabolic water. When water is scarce a camel can metabolise fats
What is HYDROPHOBIC?	Repels water
What is HYDROPHILIC?	Attracts water
State two differences between a triglyceride and a phospholipid	A triglyceride has three fatty acids, no phosphate group and is non-polar. A phospholipid has two fatty acids, one phosphate group and a hydrophilic head and a hydrophobic tail
Which end of the phospholipid molecule lies to the outside of the membrane?	The hydrophilic head
State through which part of the membrane each of the following passes in order to enter or leave a cell 1) Sodium ion 2) A lipid soluble molecule	1) Intrinsic protein 2) Phospholipid
List the four bonds present in the tertiary structure of a protein	Peptide Hydrogen Disulphide Ionic
Classify the following proteins as fibrous or globular: insulin, collagen, keratin, lysozyme (enzyme)	Insulin - globular Collagen -fibrous Keratin - fibrous Lysozyme - globular
Why is water described as a polar molecule?	A polar molecule carries an unequal distribution of electrical charge. The oxygen end has a slightly negative charge and the hydrogen end of the molecule has a slightly positive charge
State the properties of water which allow the following: How are insects able to walk on water? How are fish able to live in a frozen pond? Why does sweating keep us cool?	Pondskater - high surface tension Water has a max density at 4*c so ice floats forming an insulating layer for animals below Sweating - high latent heat
Why are the following properties of water important to living organisms? 1) It is a universal solvent 2) It is transparent	1) To allow chemical reactions to take place in solution 2) To allow light to pass through for photosynthesis
What are the two major components of a virus?	Core of nucleic acid protein coat
What does EXOCYTOSIS mean?	When a substance leaves a cell after being transported through the cytoplasm in a vesicle
What does PHAGOCYTOSIS mean?	The process by which the cell obtains solid materials that are too large to be taken i by diffusion
The following are functions of different organelles. Name the organelle in each case: 1) Protein synthesis 2) Producing glycoproteins 3) Producing ATP 4) Produces ribosomes	1) Ribosome 2) Golgi body 3) Mitochondrion 4) Nucleolus
Name the organelle in each case that possesses the following structures: 1) Cristae 2) Thylakoids 3) Cisternae	1) Mitochondrion 2) Chloroplast 3) Endoplasmic Reticulum
What is a CENTRIOLE?	Structure in cell division from which spindle fibres develop
What is PLASMODESMATA?	Strands of cytoplasm linking cells together
List three features present in a plant cell, not found in an animal cell	Chloroplasts Cell wall Large permanent vacuole
State which of the following is a cell, tissue or organ Kidney, Epithelium, Muscle, Sperm	Kidney - organ Epithelium - tissue Muscle - tissue Sperm - cell
What does BIMOLECULAR mean?	Phospholipid molecules stretched out to form two layers
What is the difference between extrinsic and intrinsic proteins found in the cell membrane?	Extrinsic proteins occur on the surface of the bilayer or partly embedded in it Intrinsic proteins extend across both layers
Glucose is water soluble and vitamin A is fat soluble. They both enter a cell by passing across the membrane. Explain how the properties of the molecules and the structure of the membrane determine the way in which these two substances pass across	Vitamin A is fat soluble and freely passes through the lipid bilayer. Large molecules such as glucose are insoluble in lipids and cannot pass through the non-polar centre of the phospholipid bilayer. Intrinsic proteins assist glucose to pass in and out of the cell by facilitated diffusion
State two features of the membrane that increase the rate of diffusion	Large surface area Thin
Explain how an increase in temperature affects the rate of diffusion	Increase in kinetic energy of molecules results in an increase in rate
How does facilitated diffusion differ from diffusion	Carrier proteins are involved in facilitated diffusion
State one similarity and one difference between facilitated diffusion and active transport	Both use carrier proteins; active transport requires energy/ATP; occurs against a concentration gradient
Name two processes that involve active transport	Muscle contraction Nerve impulse transmission Protein synthesis Uptake of minerals by roots

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AS Biology Biochemistry and Cell Structure

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