IB BIOLOGY ACTUAL EXAM PAPER 2026
QUESTIONS WITH SOLUTIONS GRADED A+
◉phospholipid. Answer: The phospholipids are not "true fats"
because they have one of the fatty acids replaced by a phosphate
group
◉natural fat. Answer: protect and insulate body organs (major
source of stored energy in the body)
◉steroid. Answer: Steroids are lipids because they are hydrophobic
and insoluble in water, but they do not resemble lipids since they
have a structure composed of four fused rings
◉carbohydrate. Answer: compound made up of carbon, hydrogen,
and oxygen atoms; major source of energy for the human body
◉nucleic acid. Answer: macromolecule containing hydrogen,
oxygen, nitrogen, carbon, and phosphorus. Forming DNA and RNA
◉lipids. Answer: macromolecule made mainly from carbon and
hydrogen atoms to form 3 fatty acids and a glycerol; includes fats,
oils, and waxes
, Lipids are a group of organic molecules that are insoluble in water
but soluble in non-polar organic solvents
Common lipids include triglycerides (fats and oils), phospholipids
and steroids
◉active site. Answer: the active site is the region of an enzyme
where substrate molecules bind and undergo a chemical reaction
◉glycogen. Answer: Glycogen is a multibranched polysaccharide of
glucose that serves as a form of energy storage in animals and fungi
◉cellulose. Answer: Cellulose is a long chain of linked sugar
molecules that gives wood its remarkable strength. It is the main
component of plant cell walls, and the basic building block for many
textiles and for paper.
◉starch. Answer: A naturally abundant nutrient carbohydrate,
(C6H10O5)n, found chiefly in the seeds, fruits, tubers, roots, and
stem pith of plants, notably in corn, potatoes, wheat, and rice, and
varying widely in appearance according to source but commonly
prepared as a white amorphous tasteless powder.
QUESTIONS WITH SOLUTIONS GRADED A+
◉phospholipid. Answer: The phospholipids are not "true fats"
because they have one of the fatty acids replaced by a phosphate
group
◉natural fat. Answer: protect and insulate body organs (major
source of stored energy in the body)
◉steroid. Answer: Steroids are lipids because they are hydrophobic
and insoluble in water, but they do not resemble lipids since they
have a structure composed of four fused rings
◉carbohydrate. Answer: compound made up of carbon, hydrogen,
and oxygen atoms; major source of energy for the human body
◉nucleic acid. Answer: macromolecule containing hydrogen,
oxygen, nitrogen, carbon, and phosphorus. Forming DNA and RNA
◉lipids. Answer: macromolecule made mainly from carbon and
hydrogen atoms to form 3 fatty acids and a glycerol; includes fats,
oils, and waxes
, Lipids are a group of organic molecules that are insoluble in water
but soluble in non-polar organic solvents
Common lipids include triglycerides (fats and oils), phospholipids
and steroids
◉active site. Answer: the active site is the region of an enzyme
where substrate molecules bind and undergo a chemical reaction
◉glycogen. Answer: Glycogen is a multibranched polysaccharide of
glucose that serves as a form of energy storage in animals and fungi
◉cellulose. Answer: Cellulose is a long chain of linked sugar
molecules that gives wood its remarkable strength. It is the main
component of plant cell walls, and the basic building block for many
textiles and for paper.
◉starch. Answer: A naturally abundant nutrient carbohydrate,
(C6H10O5)n, found chiefly in the seeds, fruits, tubers, roots, and
stem pith of plants, notably in corn, potatoes, wheat, and rice, and
varying widely in appearance according to source but commonly
prepared as a white amorphous tasteless powder.
