Bio: cells and control

Give one reason why people are short - sighted.(1)

The eye is too long.

how can short-sightedness be correct.(1)

concave lens (the squareish one)

Compare the outcomes of mitosis ad meiosis.(3)

Mitosis produces 2 new gentically indentical daughter cells but meiosis forms 4 daughter cells.mitosis cells are not gentically varied but in meiosis the cells are gentically varied. Mitosis forms diploid cells but meiosis forms haploid cells.

Compare the light intensity at a distance of 25 from the lamp.(3)

inverse square law equation: x = 1/d squared

1/25 squared

explain how a student could improve the investigation to get a more accurate measurement of the gas produced.(2)

collect gas produced

using a measuring cylinder

compare the structure of prokaryotic and eukaryotic organisms.(6)

P has a small/simple structure but E have a large/complex structure.

both had membrane, cytoplasm and ribosomes

P has membrane-bound organelles but E does not

genetic material of P cells in a single loop of DNA lies in cytoplasm but in E it is in the nucleus

P cells have additional DNA, DNA in a ring called called a plasmid

the question in the picture:

fatty acids and glycerol so lower pH of solution

Using the graph describe the effect of temperature on the activity of lipase.(2))

from 0.2 to 0.8 temperature increases from 20 to 40 degrees

explain why the activity of lipase changes above the temp of 40 degrees celsius.(2)

enzyme denatures so shape of active site changed

Explain what is meant by the 95th percentile on a graph.(2)

5% of males are taller than the males in this percentile

AT THAT AGE

The walls of the heart has different thickness.Explain this difference.(3)

left side is thicker than the right side as the left side can then pump blood at high pressure. The left side has to pump blood all around the body but the right side only pumps blood to the lungs.

Explain the effect of the coronary arteries becoming blocked on the functioning of the heart.(2)

less oxygen to the heart muscle

so heart muscle cannot respire

Describe how the stages of mitosis result of the formation of 2 diploid cells.(6)

Interphase:

DNA replication occurs before mitosis begins

Chromosomes are duplicated, creating 2 copies of each chromosone

cell increases its organelles

Prophase: Chromosomes condense and the nuclear membrane breakks down

Metaphase: Chromosomes line up along the middle of the cell

Anaphase: spindle fibres pull the copies apart to opposites ends of the cell

Telophase: New nuclear membranes form around each set of chromosomes at the ends.

The cytoplasm and the cell membrane divide to split the cell into 2

The result is 2 diploid genetically identical cells.

compare mitosis with meiosis.(2)

Mitosis is used for asexual reproduction but meiosis is used for sexual reproduction.

Mitosis produces diploid cells but meiosis produces haploid cells.

Explain the function of the reflex arc.(2)

protects the body sub-consciously

faster electrical impulses than normal

Some painkillers prevent neurotransmitters binding to receptors in a synapse.

Explain how a signal is transmitted at a synapse and how the painkillers reduce the pain felt by the person.

A synapse is a gap between 2 neurons.

signal diffused across a synapse as neurotransmitters

because electrical impulse unable to diffuse

neuron goes from high to low concentration

when enough neurotransmission taken transmission stopped goes on to the second neuron

stops enough neurotransmission to go through

painkillers sit on the receptor

to block the electrical impulse