PREGUNTAS Y RESPUESTAS TÍPICAS DEL TEMA TRES
PROPIEDADES DEL AGUA COMO REFRIGERANTE, TRANSPORTE Y HABITAT.
Responses must include reference to coolant, transport and habitat to
receive full marks.
coolant:
lots of energy required to heat water / water has a high specific heat capacity /
hydrogen bonding of water molecules;
when water evaporates energy is used;
cools organism;
eg sweating / panting / transpiration;
transport:
water is polar / universal solvent;
dissolves many organic / inorganic substances;
movement of water carries substances around organism;
eg blood / phloem / xylem / adhesion / cohesion;
medium for external transport (eg gametes);
habitat:
water is transparent;
allows light through for photosynthetic organisms;
organisms live in / on water / surface tension for surface creatures / buoyancy;
contains dissolved gases;
fish / aquatic organisms survive under ice at surface;
(Plus up to [2] for quality)
8 max
[8]
SIGNIFICADO DEL AGUA PARA LOS ORGANISMOS VIVOS
(Total 6 marks)
Features and their significance may include:
surface tension – allows some organisms (eg insects) to move on water’s surface;
polarity / capillarity / adhesion – helps plants transport water;
transparency – allows plants to photosynthesise in water / allows animals to see;
(excellent) solvent – capable of dissolving substances for transport in organisms;
(excellent) thermal properties (high heat of vaporization) – excellent coolant;
ice floats – lakes / oceans do not freeze, allowing life under the ice;
buoyancy – supports organisms;
structure – turgor in plant cells / hydrostatic skeleton;
habitat – place for aquatic organisms to live;
involved in chemical reactions in organisms;
6 max
Each feature or property must be related to living organisms in order to receive a
mark.
[6]
FUNCIÓN DE ELEMENTOS EN EL ORGANISMO.
Award [1] for each element and its role.
eg C / carbon in forming organic molecules / carbohydrates /
fats / proteins / nucleic acids;
eg H / hydrogen in forming organic molecules / carbohydrates / fats /
proteins / nucleic acids / reducing / fixing CO2 in photosynthesis;
eg O / oxygen in aerobic respiration;
eg N / nitrogen in formation of amino acids / proteins /
nucleotides / ATP / nucleic acids / DNA / RNA;
eg P / phosphorus in formation of nucleotides / ATP /
nucleic acids / DNA / RNA;
eg Ca / Ca2+ / calcium in muscle contraction / nerve transmission /
formation of bones / teeth; eg. Fe / Fe2+ / iron in
formation of hemoglobin / catalase;
eg Na / Na+ / sodium in nerve transmission / osmoregulation;
eg K / K+ / potassium in stomatal opening etc;
[4]
TRANSPORTE PASIVO A TRAVÉS DE LAS MEMBRANAS
passive transport requires no energy;
molecules move down a concentration gradient;
water moves by osmosis;
from lower solute concentration to higher solute concentration / high water
concentration to low water;
small uncharged molecules move by diffusion;
between phospholipid molecules;
charged molecules move by facilitated diffusion;
requires a protein channel;
Transporte activo a través de las membranas
goes against concentration gradient / from low concentration to high concentration;
requires hydrolysis of ATP / requires energy from ATP;
proteins in membrane utilized;
specificity of carriers;
eg Na+-K+ pump / other suitable examples;
may involve conformational change in carrier protein;
moves ions / solutes;
maintains chemical / electrical gradient;
Explain the various methods cells use to transport materials across membranes.
through endocytosis large particles are brought into cells across membranes;
through exocytosis large particles are removed from cells;
by the formation of vesicles;
active transport requiring ATP;
uses protein pumps;
to move materials against concentration gradients;
protein channels enable facilitated diffusion of molecules
down concentration gradient;
the molecules are too large or too charged to diffuse
directly through the membrane;
small polar and non-polar molecules / gases;
can diffuse directly through the membrane;
from an area of high concentration to an area of low
concentration / down the concentration gradient (until equilibrium is reached);
osmosis is the passive movement of water molecules;
across a partially / selectively permeable membrane;
from a region of lower solute concentration to a region
of higher solute concentration;
RECONOCIMEINTO DE DIFERENTES BIOMOLÉCULAS EN UN DIAGRAMA,
RESPONDE SIN MIRAR LAS RESPUESTAS!!
I.
O
CH 3
(CH 2) n
II.
O
HOH 2 C
H
C
C
C
OH
III.
H
C
H
OH
O
H
H
C
C
OH
OH
IV.
CH 2 OH
C
H H
R
H
H
C
O
N
C
C
H
H
OH
(a)
C
C
H
OH
OH
OH
OH
Identify which of the diagrams represent
(i)
the structure of glucose;
.......................................................................................................................
....
(1)
(ii)
the structure of amino acids;
.......................................................................................................................
....
(1)
(iii)
the structure of fatty acids.
.......................................................................................................................
....
(1)
(b)
Discuss which of the molecules are most similar in structure.
.................................................................................................................................
....
.................................................................................................................................
....
.................................................................................................................................
....
.................................................................................................................................
....
.................................................................................................................................
....
.................................................................................................................................
....
(3)
(Total 6 marks)
(a)
(i)
(b)
III
1
(ii)
IV
1
(iii)
I
1
II and III have the most similarities;
both have ring shaped molecules;
both have one oxygen atom in the ring;
both have the same relative amounts of C, H and O;
both have only –OH and –H linked to the carbon atoms;
both are monosaccharides / sugars / reducing sugars;
I and IV both have a carboxyl / COOH / acid group;
I and IV both are linear;
3 max
[6]
Outline the production of a dipeptide by a condensation reaction. Include the structure of a
generalized dipeptide in your answer.
(Total 5 marks)
ATENCIÓN: SÓLO AGREGO LA RESPUESTA DEL DIPÉTIDO
(ESTA ES UNA PREGUNTA MODELO TÍPICA, UTILIZÁ LA FORMA DE LA
RESPUESTA PARA RESPONDER:
A.DESCRIBA LA FORMACIÓN DE UN TRIGLICÉRIDO POR CONDENSACIÓN
INCLUYENDO LA ESTRUCTURA GENERALIZADA DE UN TRIGLICÉRIDO
EN SU RESPUESTA.
b. TODO EL RESTO DE POSIBILIDADES X EJ: LA HIDRÓLISIS DE UN DISACÁRIDO
PARA OBTENER UN MONOSACÁRIDO, LA HIDRÓLISIS DE UN
TRIGLICÉRIDO.. ETC)
carboxyl / COOH group of one amino acid reacts with amine /
NH2 group of another;
water / H2O is eliminated;
These steps can be shown diagrammatically, eg
R
R
O
H
N
C
O
H
C
N
H
C
C
H
OH
OH
H
H
condensation
H2 O
peptide / covalent bond is produced;
diagram of dipeptide, with peptide bond shown [2 max];
eg
R
O
R
O
H
N
C
C
N
C
H
OH
H
{
H
H
peptide bond
Award [1] if the two amino acids forming the dipeptide
are shown correctly. The radicals can be shown as R
or H. Award the second mark if the C-N bond is
labelled as peptide bond or dipeptide bond. The label
can include the H bonded to the N and the O double
bonded to the C.
[5]