Biology Paper 2 2019

Describe the role of enzymes in the digestion of proteins in an animal

-peptide bonds hydrolyse

-Endopeptidase works at the middle of the protein

-Exopeptidase works at the ends of the protein

-Dipeptidase works in-between amino acids

Describe the effect of increasing co2 concentration on the disassociation of oxyhaemoglobin

-increases disassociation of oxygen

-decreasea pH in blood

Describe the role of antibodies in stimulating phagocytosis

-binds to antigens

-attracts phagocytes

Explain why coloured water moves up the stalks

-Water evaporates from stalk

-creates water potential gradient

-hydrogen bonds maintains column

Describe and explain how the scientist used aseptic techniques to mo s each cube of agar onto another plate

-wash hands to kill microbes

-lift lid up slightly to prevent entry of microbes

-flame instrument to kill microbes

Describe the role of iron ions, sodium ions and phosphate ions in cells

Iron Ions:

-polar so binds to oxygen

Sodium ions:

-Co transport of amino acids into cell

-affects water potential

Phosphate Ions:

-joins nucleotides in phosphodiester bonds

-produces ATP

explain how the movement of substances across the membrane is affected by the membrane structure

-Carrier Proteins allow Active Gransport

-Channel/Carrier Proteins allow facilitated diffusion

-Number of channels/carriers determine the amount of movement

-Cholesterol affects fluidity

-Phospholipid bilateral prevents movement of charged ions