Q: Between a prokaryote and a eukaryote, which cell has a short cell division time?
A: Prokaryote.
Q: Among prokaryotes and eukaryotes, which one has shorter duration of cell cycle?
A: Prokaryotes. They have 20 mts while eukaryotic plant cell has 16 hours.
Q: Which of the phases of cell cycle is of longest duration?
A: Interphase
Q: Which tissues of animals and plants exhibit meiosis?
A: Gamet producing cells in animals show meiosis (Gametic meiosis). In Thallophyta Zygote shows meiosis (Zygotic meiosis). The spore mother cells show meiosis from Bryophytes to Angiosperms (Sporic meiosis).
Q: Which part of human body should one use to demonstrate stages in Mitosis?
A: Cells of the upper layer of the epidermis, cells of the lining of the gut and blood cells show regular mitotic divisions.
Q: What attributes does a chromatid require to be classified as a chromosome?
A: A chromatid has the following characters to be classified as a chromosome. 1. Polarity 2. DNA 3. Centromere
Q: Which of the four chromatids of a bivalent of prophase I of meiosis can involve in crossing over?
A: Four chromatids, if given numbers 1, 2 (of one chromosome) 3, 4 (another homologous chromosome of the bivalent), they involve in crossing over as follows 1, 3; 1, 4; 2, 3; and 2, 4. These pairs of chromatids are called non-sister chromatids.
Q: An anther has 1200 pollen grains. How many pollen mother cells must have been there to produce them?
A: 300 pollen mother cells (each one produces 4 pollen grains by meiosis).
Q: At what stage of cell cycle does DNA synthesis occur?
A: DNA synthesis occurs in Sphase of Interphase.
Q: It is said that one cycle of cell division in human cells (eukaryotic cells) take 24hrs. Which phase of the cell cycle, do you
think occupies the maximum part of cell cycle?
A: Interphase occupies 95% of the 24 hrs. (22 hrs 48 mts).
Q: It is observed that heart cells do not exhibit cell division. Such cells do not exhibit cell division. Such cells do not divide further and exit ……. (1) phase to enter in active stage called …… (2) of cell cycle. Fill in the blanks.
A: (1). G1 Phase (2). Quiescent stage (Go)
Q: Identify the substages of prophase I in meiosis in which synapse and desynapse are formed?
A: Homologous chromosomes show synapsis in Zygotene and desynapsis in Diplotene of Prophase I.
Q: Name the stage of Meiosis in which actual reduction in chromosome number occurs?
A: Anaphase I. Genomes separate, move and reach their opposite poles.
Q: Mitochondria and plastids have their own DNA. What is their fate during nuclear division like mitosis?
A: Mitochondria and plastids multiply in number due to the presence of DNA. They are equally distributed to the daughter cells.
Q: A cell has 32 chromosomes. It undergoes mitotic division. What will be the chromosome number during metaphase? What would be the DNA content (C) during anaphase?
A: The chromosome number during Metaphase is 32. The DNA content during anaphase is 2C.
Q: While examining the mitotic stage in a tissue, one finds some cells with 16 chromosomes and some with 32 chromosomes. What possible reasons could you give to this difference in chromosome number? Do you think cells with 16 chromosomes could have arisen from cells with 32 chromosomes or vice versa.
A: The reason is… The chromosomes divide but nucleus do not divides. Due to this the cell has 32 chromosomes. It is called endomitosis. The cells with 32 chromosomes have arisen from cells with 16 chromosomes.
Q: The following events occur during the various phases of the cell cycle. Fill the blanks with suitable answer against each.
a) Disintegration of nuclear membrane ……
b) Appearance of nucleolus ……
c) Division of centromere ……
d) Replication of DNA …..
A: a) Prophase b) Telophase c) Anaphase d) SPhase of Interphase
Q: Two key events take place during S-phase in animal cells. DNA replication and duplication of centriole. In which parts of the cell do these events occur?
A: DNA replication takes place in Nucleus. Centriole duplicates in cytoplasm.
Q: Name a cell that is found arrested in diplotene stage for months and years. Comment in 2 or 3 sentences how it completes cell cycle?
A: In oocytes of some vertebrates Diplotene lasts for months and years.
Q: The transverse section of a plant material shows the following anatomical featuresa) The vascular bundles are conjoint, scattered
and surrounded by a selerenchymatous bundle sheaths. b) Phloem parenchyma is absent. What will you identify as?
A: a) Monocot stem b) Phloem of Monocot stem
Q: Why are Xylem and Phloem called complex tissues?
A: Xylem and Phloem are made up of more than one type of cells which work together to perform a common function.
Q: How is the study of plant anatomy useful to us?
A: The study of plant anatomy is useful for a better understanding of tissue organisation of roots, stems and leaves.
Q: Protoxylem is the first formed Xylem. If the protoxylem lies radially next to Phloem what kind of arrangement of Xylem would you call it? Where do you find?
A: Xylem is exarch. It is seen in root.
Q: What is the function of Phloem Parenchyma?
A: It stores food materials and other substances like resins, latex and mucilage.