Recombination of genetic material occurs

  •       Because of synapsis

  •       Because of crossing over

  •       Because of termination of chiasmata

  •      Because of X Shaped structure

Recombination completion leads to

  •       Chromosomes attached to each other at the centromere

  •       Chromosomes attached to each other at sites of crossing over in the sister chromatids

  •       Chromosomes linked at the sites of crossing over

  •      Both A and C

Recombination completes in

  •       The end of pachytene

  •       Just before the end of pachytene

  •       the end of midphase of pachytene

  •      End of zygotene

Which of the following is not a significance of mitosis?
 
  • Restoration of nuclear/cytoplasmic ratio
  • Growth
  • Reduction of chromosome number
  • Replacement of lost cells

Meiosis has evolutionary significance because it results in 

  • genetically similar daughters

  • four daughter cells

  • eggs and sperms

  • recombinations

A bivalent consists of 

  • two chromatids and one centromere

  • two chromatids and two centromeres

  • four chromatids and two centromeres

  • four chromatids and four centromeres

Bacterium divides every 35 minutes. If a culture containing 105 cells per mL is grown for 175 minutes, what will be the cell concentration per mL after 175 minutes?

2. 35 x 105 cells

  • 5 x 105 cells

  • 3. 32 x 105 cells

  • 3

  • 174 x 105 cells

During cell division, the spindle fibres attach to the chromosomes at a region called

  • chromocentre

  • kinetochore

  • centriole

  • chromomere

What would be the number of chromosomes of the aleurone cells of a plant with 42 chromosomes in its roots tip cells?

  • 21                       

  • 42                         

  • 63                   

  • 84

Synapsis occurs between

  • a male and a female gamete

  •  mRNA and ribosomes

  • spindle fibres and centromere

  • two homologous chromosomes

Best stage to observe shape, size and number of chromosomes is

  • interphase

  • metaphase

  • prophase

  • telophase

If a diploid cell is treated with colchicine then it becomes.

  • triploid                         

  • tetraploid 

  • diploid                           

  • monoploid 

Which one of the following precedes reformation of the nuclear envelope during M-phase of the cell cycle?

  • Decondensation from chromosomes and reassembly of the nuclear lamina

  • Transcription from chromosomes and reassembly of the nuclear lamina

  • Formation of the contractile ring and formation of the phragmoplast

  • Formation of the contractile ring and transcription from chromosomes.

During mitosis ER and nucleolus begin to disappear at.

  • late prophase

  • early metaphase

  • late metaphase

  • early prophase

Mitotic anaphase differs from metaphase in possessing.

  • same number of chromosomes and same number of chromatids

  • half number of chromosomes and half number of chromatids

  • half number of chromosomes and same number of chromatids

  • same number of chromosomes and half number of chromatids

Meiosis I:
  • is always followed by interphase
  • is not followed by any period of rest
  • is followed by a period of interkinesis
  • is sometimes followed by interphase

The centrioles replicate during:

  • G1 phase
  • S phase
  • G2 phase
  • Early prophase

Bivalent chromosomes clearly appear as tetrads during:

  • Zygotene

  • Pachytene

  • Diplotene

  • Diakinesis

The beginning of diplotene is recognized by :

  • appearance of recombination nodules

  • Crossing over
  • Dissolution of synaptonemal complex
  • Appearance of chiasmata

Consider the given two statements:

l. During G1 phase the cell is metabolically active and continuously grows but does not replicate its DNA.

ll. During G2 phase, proteins are synthesized in preparation for mitosis while cell growth continues.

Of the two statements:

  • Only l is correct
  • Only ll is correct
  • Both l and ll are correct
  • Both l and ll are incorrect 

How do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis?

  • They have twice the amount of cytoplasm and half the amount of DNA.
  • THey have half the number of chromosomes and half the amount DNA.
  • They have the same number of chromosomes and half the amount of DNA.
  • They have half the number of chromosomes and one-fourth the amount of DNA.

If the DNA content of an onion tip cell is 2C at the end of the M-phase, what would be its DNA content at the end of the S-phase?

  • C

  • 2C

  • 3C

  • 4C

The cell shown in the given diagram is in:

      

  • Early prophase

  • Late prophase

  • Metaphase

  • Telophase

In oocyte of some vertebrates, the stage of meiosis I that can last for months or years would be:

  • Zygotene

  • Pachytene

  • Diplotene

  • Diakinesis

At what phase of meiosis are homologous chromosomes separated ?

  • Prophase l

  • Prophase ll
  • Anaphase l
  • Anaphase ll

The following cell, undergoing mitosis, is at:

  • Early prophase

  • Late prophase

  • Transition to metaphase

  • Early metaphase

Anaphase promoting complex (APC) is a protein degradation machinery necessary for proper mitosis of animal cells. If APC is defective in a human cell, which of the following is expected to occur?

  • Chromosomes will not condense

  • Chromosomes will be fragmented

  • Chomosomes will not segregate

  • Recombinantion of chromosome arms will occur 

DNA replication in bacteria occurs

  • during S-phase

  • within nucleolus

  • prior to fission 

  • just before transcription 

Which of the following options gives the correct sequences of events during mitosis?

  • Condensation → nuclear membrane disassembly → crossing over → Segregation → telophase

  • Condensation → nuclear membrane disassembly → arrangement at equator → centromere division → Segregation → telophase

  • Condensation → crossing over → nuclear membrane disassembly → Segregation → telophase

  • Condensation → arrangement at equator → centromere division → Segregation → telophase

During cell growth, DNA synthesis takes place in

  • S-phase                       

    (2) G1-phase

  • 2

  •  G2-phase                     

    (4) M-phase 

  • 4
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