The results for oxygen and carbon dioxide in the samples of breathed out air
taken
before and after exercise are different.
Describe and explain these differences.
In breathed out air, after exercise there is less oxygen and more carbon dioxide. As a
higher amount of energy is required during exercise for muscle contractions. The
muscle cell's respire at a faster rate. Therefore, rate of gas exchange increases. Hence,
more oxygen is absorbed into the blood and more carbon dioxide is produced (and
released into the lungs.) Moreover, the body must also "repay" the oxygen to oxidise the
lactic acid build up during excercise, thus oxygen levels exhaled still remain lower also
due to oxygen debt.
Describe what happens when an egg is fertilised by a sperm.
Sperm cell uses enzymes (from acrosome) to digest through the zona pellucida (jelly
coat.) Fusion of gametes occurs as the ehad of the sperm enters the ova's cytoplasm,
during this stage the cell membrane of the ova changes so that no other sperm may
enter. The two haploid nuclei then fuse to form a diplod zygote.
Explain why substances are transported in the phloem upwards at one time of the
year
and downwards at another.
During growing season (when photosynthesising or when food is
made i.e spring and summer.) Substances are transported down, to the roots for
storage or transported up to the flowers, fruits, seeds and new leaves.
The time of year when no photosynthesis occurs (winter.)Substances are transported
upwards from the roots, storage organ
, (or downwards) seed to the other parts of the plant like the leaves to provide them with
nutrients and cellular energy.
Define the term transpiration.
,Transpiration is the evaporation of water from the surfaces of the mesophyll cells
followed by the loss of water vapour by diffusion from the leaves through the stomata
and to the atmosphere.
Explain how water is moved to the tops of tall plants, such as the rattan palm.
Transpiration in leaves causes movement of water in the xylems
in xylem. the loss of water at the elaves at the top of the plant and reduces pressure at
the top of the plant. This creates a "transpiation pull" that draws water from the roots of
the plant. This is maintained by the cohesion of the water molecules and the adhesion
of water to the walls of the xylem. How tanspiration and intake of wate in the roots occur
continuously it maintains a continuous coloum of water in the stem.
Explain why enzymes are necessary for biological processes.
Without enzymes reactions would occur too slowly (if not at all)Enzymes speed up
reactions of many metabolic processes
ad reduce the acitivation energy for the reaction to occur. Hence the name 'Biological
Catalysts.'
Describe the events that occur in flowering plants after fertilisation to form a
seed.
After a zygote froms it divides by mitosis to form an embryo. Each part of the embryo
developsinto a different structure. Hence the formation of the radicle and plumule. The
ovule protecting the embryo devlops into a seed. Hence, the formation of the cotyledons
and the testa.
Explain how chemical digestion differs from mechanical digestion.
chemical digestion (max 2)
ref to breakdown of molecules ;
breaking bonds ;
using enzymes ;
insoluble to soluble ;
mechanical digestion (max 2)
ref to breakdown of, particle / molecule ;
ref to increase surface area (for chemical digestion) ;
to, mix /churn ;
, Describe how meiosis differs from mitosis and explain why meiosis is important
for the
production of gametes.
1 two divisions ;
2 four, cells / nuclei / gametes, produced ;
3 halves chromosome number ;
4 (diploid to) haploid ;
5 variation (between cells / nuclei / gametes) ;
6 gametes have different alleles ;
7 gives (more) variation in offspring ;
8 so chromosome number remains the same in next generation ;
Explain how the results shown in Table 2.1 support the idea that enzymes are
involved
in photosynthesis.
if no enzymes then rate should increase as temperature increases ;
but rate decreases, above 30 oC / at high temperatures ;
enzymes are denatured ;
ref to active site destroyed ;
substrate no longer fits into active site ;
reaction not catalysed / AW ;
Explain why it is necessary for the blood supply to muscles to increase during
exercise.
increase in energy demand in muscle ;
for contraction (of muscle) ;
increase in respiration in muscle ;
increase in blood flow supplies
more oxygen ;
for aerobic respiration ;
more glucose ;
more, fat / fatty acids ;
increase in blood flow removes
taken
before and after exercise are different.
Describe and explain these differences.
In breathed out air, after exercise there is less oxygen and more carbon dioxide. As a
higher amount of energy is required during exercise for muscle contractions. The
muscle cell's respire at a faster rate. Therefore, rate of gas exchange increases. Hence,
more oxygen is absorbed into the blood and more carbon dioxide is produced (and
released into the lungs.) Moreover, the body must also "repay" the oxygen to oxidise the
lactic acid build up during excercise, thus oxygen levels exhaled still remain lower also
due to oxygen debt.
Describe what happens when an egg is fertilised by a sperm.
Sperm cell uses enzymes (from acrosome) to digest through the zona pellucida (jelly
coat.) Fusion of gametes occurs as the ehad of the sperm enters the ova's cytoplasm,
during this stage the cell membrane of the ova changes so that no other sperm may
enter. The two haploid nuclei then fuse to form a diplod zygote.
Explain why substances are transported in the phloem upwards at one time of the
year
and downwards at another.
During growing season (when photosynthesising or when food is
made i.e spring and summer.) Substances are transported down, to the roots for
storage or transported up to the flowers, fruits, seeds and new leaves.
The time of year when no photosynthesis occurs (winter.)Substances are transported
upwards from the roots, storage organ
, (or downwards) seed to the other parts of the plant like the leaves to provide them with
nutrients and cellular energy.
Define the term transpiration.
,Transpiration is the evaporation of water from the surfaces of the mesophyll cells
followed by the loss of water vapour by diffusion from the leaves through the stomata
and to the atmosphere.
Explain how water is moved to the tops of tall plants, such as the rattan palm.
Transpiration in leaves causes movement of water in the xylems
in xylem. the loss of water at the elaves at the top of the plant and reduces pressure at
the top of the plant. This creates a "transpiation pull" that draws water from the roots of
the plant. This is maintained by the cohesion of the water molecules and the adhesion
of water to the walls of the xylem. How tanspiration and intake of wate in the roots occur
continuously it maintains a continuous coloum of water in the stem.
Explain why enzymes are necessary for biological processes.
Without enzymes reactions would occur too slowly (if not at all)Enzymes speed up
reactions of many metabolic processes
ad reduce the acitivation energy for the reaction to occur. Hence the name 'Biological
Catalysts.'
Describe the events that occur in flowering plants after fertilisation to form a
seed.
After a zygote froms it divides by mitosis to form an embryo. Each part of the embryo
developsinto a different structure. Hence the formation of the radicle and plumule. The
ovule protecting the embryo devlops into a seed. Hence, the formation of the cotyledons
and the testa.
Explain how chemical digestion differs from mechanical digestion.
chemical digestion (max 2)
ref to breakdown of molecules ;
breaking bonds ;
using enzymes ;
insoluble to soluble ;
mechanical digestion (max 2)
ref to breakdown of, particle / molecule ;
ref to increase surface area (for chemical digestion) ;
to, mix /churn ;
, Describe how meiosis differs from mitosis and explain why meiosis is important
for the
production of gametes.
1 two divisions ;
2 four, cells / nuclei / gametes, produced ;
3 halves chromosome number ;
4 (diploid to) haploid ;
5 variation (between cells / nuclei / gametes) ;
6 gametes have different alleles ;
7 gives (more) variation in offspring ;
8 so chromosome number remains the same in next generation ;
Explain how the results shown in Table 2.1 support the idea that enzymes are
involved
in photosynthesis.
if no enzymes then rate should increase as temperature increases ;
but rate decreases, above 30 oC / at high temperatures ;
enzymes are denatured ;
ref to active site destroyed ;
substrate no longer fits into active site ;
reaction not catalysed / AW ;
Explain why it is necessary for the blood supply to muscles to increase during
exercise.
increase in energy demand in muscle ;
for contraction (of muscle) ;
increase in respiration in muscle ;
increase in blood flow supplies
more oxygen ;
for aerobic respiration ;
more glucose ;
more, fat / fatty acids ;
increase in blood flow removes
