JAMB Biology Past Questions & Answers - Page 345

1,721.

Which of the following statement is NOT true of enzymes? They

A.

Are proteins

B.

Need cofactors to activate them

C.

Are sensitive in their action

D.

Are specific in their action

E.

Can withstand high temperature

Correct answer is E

No explanation has been provided for this answer.

1,722.

Osmosis can be defined as the movement of 

A.

Molecules from solution of higher concentration to low concentration

B.

Molecules from solution of low concentration to high concentration

C.

Water from solution of high concentration to low concentration

D.

Water across a semi-permeable membrane from solution of low concentration to high concentration

E.

Water across a semi-permeable membrane from solution of high concentration to low concentration

Correct answer is D

Osmosis is a special case of diffusion in which only water molecules move from a region of higher to lower water potential through a semi-permeable membrane.

1,723.

The exchange of genes between homologous chromosomes is called

A.

test cross

B.

back cross

C.

crossing-over

D.

mutation

Correct answer is C

No explanation has been provided for this answer.

1,724.

The mammalian organ through which nourishment and oxygen diffuse into a developing embryo is called 

A.

Amnion

B.

Chorion

C.

Umbilical cord

D.

Oviduct

E.

Placenta

Correct answer is E

No explanation has been provided for this answer.

1,725.

The greatest contribution to genetic studies was made by

A.

Thomas Morgan

B.

Gregor Mendel

C.

Charles Darwin

D.

Robert Hooke

Correct answer is B

No explanation has been provided for this answer.