Cell & Nuclear Division (SL IB Biology)

The photomicrograph shows cells in different stages of mitosis.

In which order do these stages occur?

Which of the following do(es) not happen during an animal cell cycle?

1. DNA is transcribed and translated
2. The spindle is formed from microtubules
3. A cell plate forms to divide daughter cells
4. Plasma membrane is pulled inwards around the cell equator to form a cleavage furrow

Each of the following events takes place during mitosis:

In which order do the events take place?

The diagram shows the chromosomes of a squashed cell during mitosis.

What is the stage of mitosis and the haploid chromosome number for this cell?

The diagram below shows a plant life cycle. It includes unfamiliar stages such as ‘sporophyte’ and ‘gametophyte’ that are not found in human life cycles.

What process is taking place at the stage marked X on the diagram? 

Which of the individuals described below does the following karyogram represent?

Which of the following gives an accurate definition of genetic recombination?

Which of the following most accurately describes the events that occur in meiosis I?    

The diagram shows a pair of homologous chromosomes at the beginning of prophase I of meiosis, and four possible examples of crossing over, A - D

Which of the four representations of crossing over cannot occur in meiosis I?

For a eukaryotic organism with a diploid number of 14, which option gives the number of chromosome combinations that can occur as a result of random orientation in meiosis?

Note that all the equations below are mathematically correct.

Which of the following statements correctly describes meiosis?

The diagram below shows the life cycle of a fern. The term 2n is used to represent diploid cells and the term n is used to represent haploid cells.

Which stage represents meiosis?

Which events are taking place at stages 1, 2, and 3 in the diagram of meiosis below?

Which of the following statements about genetic variation and meiosis are correct? 

1. Meiosis generates genetic variation through crossing over, random orientation, and random fusion of gametes.
2. The number of different combinations of chromosomes that are possible as a result of random orientation is 2ⁿ, where n is the number of chromosomes in a diploid cell.
3. Crossing over can take place at any location along a chromosome

A group of scientists carried out a study looking at the relationship between the number of crossing over events taking place during meiosis and the distance between the crossing over events and the centromere in male trout (a species of fish).  Some of their results are shown in the graph below.

What can be concluded from the graph?

Chromosome non-disjunction in the sex chromosomes can result in gametes that contain more than one sex chromosome. 

The graph below shows the results of a study looking at the impact of age on sex chromosome non-disjunction in men.

How many XY sperm would be predicted in a sample of 1 000 000 sperm from a 45 year old man?

Some scientists were investigating mitosis in plant cells. They applied a chemical agent called colchicine which interferes with tubulin proteins in the cytoplasm. An image of some chromosomes from a treated cell can be seen below.

How does treatment with colchicine prevent the progression of cell division in plant cells?

Which of the following is the best explanation of why the lengths of DNA exchanged during crossing-over tend to be the same length as each other?

The micrographs below show cells undergoing meiosis.

Which sequence correctly identifies the stage of meiosis in each micrograph from left to right?

The micrograph below shows an image of a cell undergoing meiosis.

Which stage of meiosis can be seen in the image, and why?

The following choices each show a bivalent. 

Along the length of the bivalent are some values of probability.

Which choice reflects the most likely probabilities of a chiasma forming at each of the positions shown?

Which row best describes an organism whose diploid number is 16 and whose body cells have an amount of DNA, x?

The fungus Sordaria fimicola is an excellent organism for observing the effects of meiosis because its gametes (spores) are coloured and can be observed under a microscope. 

Wild-type fungus has black spores. Another variety has tan spores.

The allele for black spores is B and the allele for tan spores is b.

These can be crossed to produce a diploid zygote, which can then undergo meiosis to produce spores. In this species, a final mitotic division results in 8 spores produced as shown below.

Each zygote produces its eight spores in a structure called an ascus, in which the eight spores line up to reveal the alignment of homologous chromosomes during the meiotic division that led to their formation. 

A microscope image of some asci is shown below.

Which asci, labelled 1 - 4 in the microscope view above, show evidence that crossing over has taken place?