Biology_2013_STPM Term 3_Structure

Fluctuation of population in fresh water lake ecosystem is shown in the diagram.

State an example of a producer and a primary consumer.

• A

• B

• C

• D

Answer explanation

Producer :

Water weeds Elodea

Primary consumer: Herbivorous fish

Example: carp

State the relationship between the population of a producer and a primary consumer. ( 1 mark)

• A

• B

• C

• D

Answer explanation

Positively correlated. The population of a primary consumer as the producer increases and vice versa.

Explain why the population decreases significantly by May and June despite the favorable condition of light and temperature. ( 2 marks )

• A

• B

• C

• D

Answer explanation

This is due to the decrease in nutrients. With lesser nutrients, the population of the producer cannot grow.

State the most likely source of the increase in nutrient that begins in October until November.

( 1 mark )

• A

• B

• C

• D

Answer explanation

Release of nutrients when the producer and primary consumer die and decompose.

State two factors that would influence the fluctuation of the population. (2 marks)

• A

• B

• C

• D

Answer explanation

Competition, predation.

The process of DNA replication at one of the replication fork is shown in Diagram 1, while part of the steps involved in the synthesis of one of the new DNA strands shown in Diagram 2.

Name the strands P and Q.

• A

• B

• C

• D

Answer explanation

P : Lagging strand

Q : Leading strand

Name the structure S.

• A

• B

• C

• D

Answer explanation

Okazaki fragment.

Name the enzymes and the processes that are involved in Steps Ⅰ and Ⅱ.

• A

• B

• C

• D

Answer explanation

Step Ⅰ :

Enzyme : DNA Polymerase

Process : Line up nucleotides and form phosphodiester bonds.

Step Ⅱ :

Enzyme : Ligase

Process : To join Okazaki fragments and form longer DNA stands.