1.1 chemical elements and biological compounds Flashcards
what are the four key inorganic ions?
magnesium, iron, phosphate, calcium.
what is magnesium
needed for in plants? why?
it is essential for photosynthesis as it is a constituent of chlorophyll.
what is iron a constituent of?
haemoglobin.
what is phosphate used to make?
it is used to make nucleotides such as ATP, DNA, and RNA.
what is phosphate a constituent of?
phospholipids found in biological membranes.
what do phosphate and calcium do to bones (and teeth for calcium)?
harden them.
why is calcium in plant cells?
it strengthens the cell wall.
what is a polar molecule? an example?
a molecule that has no overall charge due to it having both a positively charged end and a negatively charged end. water molecules are polar (often called dipole).
what kind of bonds form to make a molecule of water and where?
hydrogen bonds form between the + on a hydrogen atom of one molecule and the - on the oxygen atom of another molecule.
what is an organic ion?
a molecule that has a high proportion of carbon and hydrogen atoms.
what is an inorganic ion?
a molecule or ion that has no more than one carbon atom.
what is a micronutrient? some examples?
minerals needed in minute concentrations, e.g copper and zinc.
what is a macronutrient?
minerals needed in small concentrations.
why is water a good solvent?
because of their polarity, water molecules are attracted to other water molecules and charged particles. this helps charged particles dissolve in water.
why is water referred to as the universal solvent?
a large number of substances can easily dissolve in water.
why is water a metabolite?
it is used in many biochemical reactions as a reactant.
what does high specific heat capacity mean?
a large amount of heat energy is needed to raise its temperature.
why does water have a high specific heat capacity?
hydrogen bonds between water molecules restrict their movement, resisting an increase in kinetic energy so the temperature does not increase.
why is it beneficial that water has a high specific heat capacity?
it prevents large fluctuations in water temperature to keep aquatic habitats stable and to allow enzymes to work efficiently in cells.
what does high latent heat of vaporisation mean?
a lot of heat energy is needed to change water from a liquid to a vapour.
why is it beneficial that water has a high latent heat of vaporisation?
it is important in temperature control - heat is used to vaporise water from sweat on the skin/leaf’s surface. the surface cools as sweat evaporates.
how is water cohesive?
water molecules attract eachother, forming hydrogen bonds. the large amount of hydrogen bonds stick the molecules together to form a lattice.
what is a benefit of water being cohesive?
it allows volumes of water to be drawn up xylem vessels.
how and why does water have a high surface tension?
cohesion between water molecules at the surface of a body of water produce tension to support the bodies of insects.
why does water have a high density?
it provides support and buoyancy as a habitat for aquatic organisms.
at what temperature is water’s maximum density?
4°C.
why is ice less dense than water?
hydrogen bonds in ice hold the molecules further apart.
why does water need to be transparent?
to allow light to pass through so plants can photosynthesise.
what is the single monomer unit of a carbohydrate?
a monosaccharide.
what is the name of 2 monosaccharides bonded together?
a disaccharide.
what happens in a condensation reaction?
a molecule of water is removed from 2 monosaccharides and a glycosidic bond forms between them, creating a disaccharide.
what is hydrolysis?
a molecule of water is added to a disaccharide to break the glycosidic bond and split it back into 2 monosaccharides.
where is the hydroxyl group on an alpha glucose molecule?
on the bottom of carbon 1.
where is the hydroxyl group on a beta glucose molecule?
on top of carbon 1.
what is maltose made up of? what is it used for?
2 alpha glucose molecules. it is used in germinating seeds.
what is sucrose made up of? what is it used for?
glucose + fructose. it is used in transport in phloem of flowering plants.
what is lactose made up of? where is it found?
glucose + galactose. it is found in mammalian milk.
how do you test for a reducing sugar?
equal volumes of solution and Benedict’s reagent are heated to 70°C. if a reducing sugar is present, it will change from blue to brick-red.
how do you detect a non-reducing sugar?
the solution must be heated with HCl to break it into its monosaccharides. then Benedict’s reagent and an alkali are added, and the solution will turn brick-red if a non reducing sugar is present.
what are 3 features of polysaccharides that make them most suitable for storage?
they are insoluble - osmotically inert, they are compact molecules, and carry a lot of energy in their C-H and C-C bonds.
what is starch made up of?
it is made up of a-glucose molecules and contains the 2 polymers amylose and amylopectin.
how is amylose formed?
a-1,4 glycosidic bonds form a chain that coils into a helix of amylose.
how is amylopectin arranged?
it has chains of glucose monomers linked with a-1,4 glycosidic bonds and is cross linked with a-1,6 glycosidic bonds and fit inside amylose.
what is one property of starch?
it is osmotically inert - it does not affect the water potential of the cell as it is insoluble.
what is glycogen?
the main storage product in animals. it forms granules in cells and acts as an energy store.
why is glycogen more branched than amylopectin?
