Biology by Bradford
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The subtopic in the middle and eleven tasks round it: label six diagrams, complete a table and fill 62 gaps. Every box is standard level. Type into the blanks and check them, or print it on A4, Letter or A3 with an answer key.
Polysaccharides, polypeptides and nucleic acids are polymers: chains of . Each link is made by a reaction, which releases a molecule of water. Digestion breaks the links again by : for each one a water molecule is split, its –H joining one of the freed units and its the other.
Alternate monomers are turned , which keeps each chain . Chains lie side by side in bundles, cross-linked many times over, giving plant cell walls great .
Kinks stop the chains packing closely, so the more kinks, the the melting point. Plants store energy in , rich in kinked chains and liquid at room temperature; endotherms store it in , rich in straight chains and solid at room temperature.
Lipids, among them fats, oils, waxes and steroids, dissolve in solvents but only sparingly in water. Triglycerides are stored in tissue. Gram for gram they release about as much energy as carbohydrates, and being hydrophobic they are stored without water, so the store is light. They conduct heat poorly, so a thick layer, such as a seal's , insulates an endotherm living in cold water.
A covalent bond is a pair of electrons by two atoms. A carbon atom can form up to of them, as single or bonds, with other carbon atoms or with other non-metals such as hydrogen, oxygen and nitrogen. So carbon builds chains, or unbranched, and single or multiple : the frameworks of a vast diversity of compounds.
The two rings with six carbons are . Glucose is small and polar, so it is and easily carried in blood plasma. It is chemically , and its in respiration releases plenty of energy.
A glycoprotein is a protein with chains attached. Facing out from the cell surface membrane, they let cells one another. The ABO blood groups are an example: red blood cells of group A carry the A , group AB carry both A and B, and group carry neither.
123| Monomer | Branches | Found in | |
|---|---|---|---|
| Starch | some | plants | |
| Glycogen | |||
| Cellulose | plant cell walls |
Coiling and branching make starch and glycogen, the two energy stores, . Their huge molecules are almost , and monomers are easily added by condensation or released by as the store is built up or used.
Each link is made by a reaction. The molecule on the left is a ; the one on the right, with its charged head, is a .
Phospholipids are : one part of each molecule is attracted to water and the other repelled by it. In water they arrange themselves as a . Non-polar hormones such as oestradiol and pass straight through it.
A covalent bond is a pair of electrons shared by two atoms. A carbon atom can form up to four of them, as single or double bonds, with other carbon atoms or with other non-metals such as hydrogen, oxygen and nitrogen. So carbon builds chains, branched or unbranched, and single or multiple rings: the frameworks of a vast diversity of compounds.
Polysaccharides, polypeptides and nucleic acids are polymers: chains of monomers. Each link is made by a condensation reaction, which releases a molecule of water. Digestion breaks the links again by hydrolysis: for each one a water molecule is split, its –H joining one of the freed units and its –OH the other.
The two rings with six carbons are hexoses. Glucose is small and polar, so it is soluble and easily carried in blood plasma. It is chemically stable, and its oxidation in respiration releases plenty of energy.
| Monomer | Branches | Found in | |
|---|---|---|---|
| Starch | α-glucose | some | plants |
| Glycogen | α-glucose | more | animals |
| Cellulose | β-glucose | none | plant cell walls |
Coiling and branching make starch and glycogen, the two energy stores, compact. Their huge molecules are almost insoluble, and monomers are easily added by condensation or released by hydrolysis as the store is built up or used.
Alternate monomers are turned upside down, which keeps each chain straight. Chains lie side by side in bundles, cross-linked many times over, giving plant cell walls great tensile strength.
A glycoprotein is a protein with carbohydrate chains attached. Facing out from the cell surface membrane, they let cells recognise one another. The ABO blood groups are an example: red blood cells of group A carry the A antigen, group AB carry both A and B, and group O carry neither.
Each link is made by a condensation reaction. The molecule on the left is a triglyceride; the one on the right, with its charged head, is a phospholipid.
Kinks stop the chains packing closely, so the more kinks, the lower the melting point. Plants store energy in oils, rich in kinked chains and liquid at room temperature; endotherms store it in fats, rich in straight chains and solid at room temperature.
Lipids, among them fats, oils, waxes and steroids, dissolve in non-polar solvents but only sparingly in water. Triglycerides are stored in adipose tissue. Gram for gram they release about twice as much energy as carbohydrates, and being hydrophobic they are stored without water, so the store is light. They conduct heat poorly, so a thick layer, such as a seal's blubber, insulates an endotherm living in cold water.
Phospholipids are amphipathic: one part of each molecule is attracted to water and the other repelled by it. In water they arrange themselves as a bilayer. Non-polar hormones such as oestradiol and testosterone pass straight through it.