The mechanisms that contribute to the genetic variation arising from sexual reproduction include:

I:	Independent assortment of chromosomes
II:	Crossing over
III:	Random fertilization

1.	I and II only	2.	I and III only
3.	II and III only	4.	I, II and III

At which stage of mitosis are chromosomes usually photographed in the preparation of a karyotype?
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase

A prolonged resting phase in oogenesis as seen in many vertebrate oocytes is called as:

Place stages of Prophase I in correct order.
1. diakinesis, diplotene, leptotene, pachytene, zygotene.
2. diplotene, leptotene, pachytene, zygotene, diakinesis.
3. leptotene, pachytene, diakinesis, diplotene, zygotene.
4. leptotene, zygotene, pachytene, diplotene, diakinesis

DNA replication takes place during :

Identify the human cell for which the interphase period lasts the entire life of a person.

Consider the following functions:

Which of the above functions are carried out by a plant cell before it divides?

The duration of which of the following is constant in most cell types?
1. G₁ phase, S phase and G₂ phase
2. S phase, M phase and G₁ phase
3. S phase, G₂ phase and M phase
4. G₁ phase, M phase and G₂ phase

Consider the following statements:
I. G₀ phase is viewed as either an extended G₁ phase where the cell is neither dividing nor preparing to divide or as a distinct quiescent stage which occurs outside of the cell cycle.
II. In gamete production interphase is succeeded by meiosis.
III. In programmed cell death interphase is followed or preempted by apoptosis.

The correct statements include:

Cyclins and cyclin-dependent kinases (CDKs) are:
1. Two key classes of regulatory molecules that determine a cell's progress through the cell cycle
2. The products of the proto-oncogenes in a eukaryotic cell
3. Two very important promoters that are involved in oncogenes
4. Mediators of apoptosis