Plant Development Biology - Questions from Morphogenesis and organogenesis in plants:
1.Floral organ development is controlled by overlapping expression of ‘A’ class, ‘B’ class and ‘C’ class genes in different whorls. In an Arabidopsis mutant, the flowers had sepals, sepals, carpels and carpels in the four whorls. Mutation in which one of the following is the cause for the mutant phenotype? (CSIR Life Sciences Dec, 2015)
1. ‘A’ class gene alone
2. ‘B’ class gene alone
3. ‘A’ and ‘B’ class genes
4. ‘C’ class gene alone
Ans: 2. ‘B’ class gene alone
2. Sperm cell behaviour during double fertilization in Arabidopsis can be stated as follows. Identify the INCORRECT statement: (CSIR Life Sciences June, 2016)
1. Pollen tube bursts and discharges sperm cells.
2. Sperm cells produce pollen tubes and enter into female gametophyte.
3. The receptive antipodal cells break down when pollen tube enters the
4. One sperm nucleus fuses with the egg cell and the other fuses with the central cells
Ans: 2 and 3
3. Rhizobial genes that participate in legume nodule formation are called nodulation (nod) gens. The nodD-encoded protein (CSIR Life Sciences June, 2016)
1. is an acetyl transferase that adds a fatty acyl chain to the Nod factor.
2. binds to the nod box and induces transcription of all nod genes.
3. catalyzes the linkage of N-acetyl glucosamine residues.
4. influences the host specificity of Rhizobium.
Ans: 2. binds to the nod box and induces transcription of all nod genes.
4. Which one of the following statements is WRONG? (CSIR Life Sciences June, 2016)
1. The megasporocyte develops within the megasporangium of the ovule
2. Megasporocyte undergoes meiosis to produce four haploid megaspores
3. All the four megaspores undergo several mitotic divisions to form female gametophyte in most angiosperms
4. Female gametophyte is haploid
Ans: 3. All the four megaspores undergo several mitotic divisions to form female gametophyte in most angiosperms