biology past paper corrections 2023

State one feature of alveoli that provides an efficient gas exchange surface

Single layer of epithelium cells

What is smooth muscles function in the bronchioles?

Contracts to close bronchiole

There are stronger bonds between chitin and chitnase so the bonds in chitin are under strain, which lowers activation energy.

There are gradual change in the width of the cell wall in species A over many years

But there is no evidence that these changes to the cell wall were advantageous and increases their chance of survival

Temperature is not known so cannot conclude the effect it has on cholesterol.

Cholesterol increases fluidity at lower temperatures.

Cholesterol decreases fluidity at lower high temperatures.

The ECG in a bird has a QRS wave moving down not up

They have a faster heart rate than humans.

Starch and glycogen are polysaccharides. Starch is present in plant cells, and glycogen is present in animal cells. Glucose is a monosaccharide present in both types of cell.

Outline how the different properties of glucose, starch and glycogen relate to their functions in cells.

Glucose is soluble

Has chemical energy in bonds

Starch and glycogen are insoluble and compact

Used as an energy store

outline the structure and function of phloem tissue in the stem of a herbaceous dicotyledonous plant.

Sieve tube element

• translocation

• Transports assimilates up and down plant

• Allows mass flow

• Living cell

• Long hollow tubes

• No nucleus

• Pores to allow solutes through

Companion cells

• needed to help the sieve tube elements survive

• Gains sucrose using proton pump

• Loads sucrose into STE

• Lots of mitochondria

• Large nucleus

• Plasmodesmata connecting STE

One use of OH- ions in a biological process

Catalyses reactions

Lipids

• test tube, filter paper and funnel, pipette

• Emulsion test

• Add test solution to ethanol

• Mix with water

• Can filter using water

• Clear to cloudy

Starch

• test tube, pipette Emulsion

• Add a few drops of iodine to test solution

• Brown/orange to blue-black

How would students use a calorimeter to determine glucose concentration of another test solution?

Calibrate colorimeter with distilled water

Add red filter

Measure light absorption of sample

Properties of collagen that makes it suitable for being a protein found in ligaments.

Fibrous

Insoluble

Suggest and explain how stem cells might be used to help treat Parkinson’s disease

Stem cells can differentiate into nerve cells

Which can replace nerve cels in brain

How is palisade cell adapted to its function

Many chloroplasts for photosynthesis

Large vacuole to maintain turgor pressure

What is the cofactor for carbonic anhydrase?

Zn2+