STPM Biology 2023 Term 1 MCQ

Which are true about amylopectin?

I Has osmotic influence in the cell

II Has more branches than amylose

Ill Turns to dark blue when iodine is added

IV Possesses 1,4-glycosidic and 1,6-glycosidic bonds

• I and III

• I and IV

• II and III

• II and IV

Lipid contains more energy than carbohydrate. Which is the reason for the difference?

• The process of phosphorylation occurs

• The presence of carboxyl group

• The presence of glycerol group

• The process of oxidation occurs more often

Which is not true about nucleotides?

• Thymine is found only in DNA.

• Adenine, guanine and cytosine are found in DNA and RNA.

• Uracil is found only in RNA and can be replaced with thymine.

• Adenine pairs with thymine or uracil, and guanine pairs with cytosine.

The chromatogram for the separation of three pigments, P, Q and R, is shown in the diagram. Which is true about the pigments?

• P is bigger than Q.

• P has the highest charge.

• Q has a higher solubility in the solvent compared to R

• P has higher adsorption towards the chromatograph~ paper.

Which is the unique characteristic of prokaryotes?

• The presence of nucleoid

• The presence of linear DNA

• The presence of 80S ribosome

• The presence of 9+2 flagella

Which is not the function of endoplasmic reticulum?

• Involves in lipid synthesis

• Involves in protein synthesis

• Forms compartments in the cell

• Packages proteins to be exported out of the cell

The fluid mosaic model of membrane structure is shown in the diagram. Which are true about X?

I Involves in cell-cell recognition

II Involves in sticking cells in tissues

ill Contributes to the amphipathic properties of the membrane lipid

IV Provides selective transport for the molecules across the membrane

• I and II

• I and IV

• II and III

• III and IV

Which process involves the formation of cytoplasmic extension for bulk transport across the plasma membrane?

• Pinocytosis

• Phagocytosis

• Exocytosis

• Receptor-mediated endocytosis

Which statement is not true about an induced fit model?

• The active site of the enzyme is specific for one substrate only.

• The mechanism causes stressing and distortion of the chemical bonds on the substrates.

• The enzyme molecule moulds around the substrate after the enzyme binds to the active site.

• The structure of the enzyme returns to its original conformation after the product is released.

The Lineweaver-Burk plot for the rate of reactions using two enzymes, X and Y, that involved the same substrate is shown in the graph.

Which statements are true about the Lineweaver-Burk plot?

I K_M value of X is higher.

II X has a higher V_max value.

III Y has a higher affinity towards the substrate.

IV The reaction that is catalysed by X produces more products when the concentration of substrate is limited.

• I and II

• I and III

• II and IV

• III and IV