2019 BIO P1: questions i got wrong/learning points

brute learn food tests and ways to help the heart

function of the nucleus

controls the cell

name one type of cell that does not contain a nucleus

red blood cell

2 advantages of using an electron microscope rather than a light microscope

• higher magnification

• higher resolution

how to control spread of malaria

• use of mosquito control methods / preventing mosquitoes from breeding

• changing behavior to avoid being bitten by mosquitoes

• mosquito nets

how does the skin prevent pathogens from entering the body

• acts as a barrier

• as it is a tough outer layer covering the whole body

• the sebum on the surface of the skin repels pathogens

• platelets form scabs over cuts on the skin

• and scabs form a barrier

how do eyes prevent pathogens from entering

• they produce tears

• which contain enzymes that can kill bacteria

• tears are also antiseptic

the stomach has HCl acid which can kill bacteria in what two things?

food AND mucus

what cells are formed after an immune response? what do these do?

memory cells

give a more rapid response if pathogen re-enters body

a way to improve a method so results are more valid (ALWAYS in the MS)

repeat and caluclate a mean

things to control in RP4 (pondweed experiment) to make results more valid

• water temp

• conc of CO2

• distance of bulb from pondweed

• mass of pondweed

how is volume of water lost from leaves controlled? (1)

by the guard cells opening and closing the stomata

describe the transport of water through a plant from the roots to the atmosphere (3)

• water is transported in xylem

• water evaporates from leaves

• through the stomata

sometimes the valves in the heart start to leak. explain why a person with a leaking valve has difficulty exercising. (4)

• backflow can occur or some blood flows backwards

• less blood leaves the heart so less blood is pumped around the body or some blood stays in the heart

• less oxygen supplied to muscles / cells

• (so) less aerobic respiration

• (so) less energy released

• (so) less (efficient) muscle contraction

- anaerobic respiration takes place

• less (efficient) removal of lactic acid or lactic acid builds up or oxygen debt occurs

• (lactic acid building up) causes muscle fatigue

• less (efficient) removal of carbon dioxide (from blood)

why would a plant lose a lot of water (apart from HALT conditions)

PLANT HAS MORE:

• stomata

• leaves

• bigger leaves

• greater total surface area of leaves

name a chemical used to test for glucose

benedict’s reagent

Describe a test that could be used to show that a person’s urine contains glucose (2 marks) (mention test and positive result?)

test = add benedict’s reagent to urine AND heat

positive result = urine should change from blue to brick red

The body cells of a person with untreated diabetes lose more water than the body cells of a person who does not have diabetes. Explain how diabetes can cause the body cells to lose more water. (3)

• the blood is more concentrated or less dilute (than the solution in the cells)

• (so) water moves out of cells by osmosis

• water moves through a partially permeable membrane

Glucose is absorbed into the blood in the small intestine by both diffusion and active transport. Describe how the small intestine is adapted for efficient absorption. (5)

• projections / folds / villi provide a large surface area

• walls of projections / folds / villi / capillaries are thin / one cell thick for shorter absorption / diffusion distance

• (small intestine is) very long, increasing time (for absorption)

• good / efficient blood supply to maintain concentration gradient

• cells have many mitochondria for (aerobic) respiration for active transport

• or cells have many mitochondria for energy release for active transport

Define the term double circulatory system. (1)

blood is pumped to the lungs by right side of the heart and blood is pumped to the body by the left side of the heart

in an axolotl, explain why having only one ventricle makes the circulatory system less efficient than having 2 ventricles. (2)

oxygenated and deoxygenated blood mixes

(so) less oxygen reaches the body / tissues / cells

Explain why an axolotl may die in water with a low concentration of oxygen. (4)

• concentration gradient (of oxygen) is shallow(er) / less steep

• (therefore) less oxygen diffuses into blood / cells / gills

• (so) less (aerobic) respiration occurs so less energy is released / available

• (so) less metabolism

define enzyme (2)

• a chemical which catalyses reactions in living organisms

• which is specific to the substrate it acts on

Carbohydrase is an enzyme produced by the pancreas. Name two other organs in the digestive system that produce carbohydrase (2)

• salivary gland

• small intestine

The pancreas produces digestive enzymes.

One symptom of pancreatic cancer is weight loss.

Explain how pancreatic cancer may cause a person to lose weight.

Do not refer to hormones in your answer. (4)

• reduced enzyme production from pancreas

• food is not digested fully

• less glucose / sugar passes into the blood(stream)

• (so) less glucose available for respiration

• so more body fat used up in metabolism / respiration

  (last 2 points = part of same mark)

The drug was trialled before it was licensed for use.

To improve validity of the results in the trial:

• some patients were given a placebo

• a double-blind trial was used.

Give reasons why a placebo and a double-blind trial were used (2)

to avoid the patients thinking they feel better with the drug or to take into account a psychological effect

• as a control / comparison

• to avoid bias(ed results)

A monoclonal antibody has been produced to treat pancreatic cancer. Explain how the monoclonal antibody works to treat pancreatic cancer. (3)

monoclonal antibody is attached to radioactive substance

monoclonal antibody will (only) attach to / target (antigen on) cancer cells / tumour

(so) radioactive substance will (bind to cancer cells and) stop them growing / dividing