In maize, hybrid vigour is exploited by:
1. bombarding the seeds with DNA
2. crossing of two inbred parental lines
3. harvesting seeds from the most productive plants
4. inducing mutations
In gymnosperms, the pollen chamber represents:
| 1. | a cell in the pollen grain in which the sperms are formed |
| 2. | a cavity in the ovule in which pollen grains are stored after pollination |
| 3. | an opening in the megagametophyte through which the pollen tube approaches the egg |
| 4. | the microsporangium in which pollen grains develop |
During transcription, RNA polymerase holoenzyme binds to a gene promoter and assumes a saddle-like structure. What is its DNA-binding sequence?
| 1. | TIAA |
| 2. | AATI |
| 3. | CACC |
| 4. | TATA |
In the prothallus of a vascular cryptogam, the antherozoids and eggs mature at different times. As a result:
| 1. | there is no change in the success rate of fertilization |
| 2. | there is a high degree of sterility |
| 3. | one can conclude that the plant is apomictic |
| 4. | self-fertilization is prevented |
Industrial melanism as observed in peppered moths proves that:
| 1. | The true black melanic forms arise from a recurring natural selection |
| 2. | The melanic form of the moth has no selective advantage over the lighter form in an industrial area |
| 3. | The lighter-form moth has no selective advantage either in polluted industrial areas or non-polluted areas |
| 4. | Melanism is a pollution-generated feature |
Differentiation of organs and tissues in a developing organism is associated with:
1. developmental mutations
2. differential expression of genes
3. lethal mutations
4. deletion of a gene
The first acceptor of electrons from an excited chlorophyll molecule of photosystem II is:
| 1. | cytochrome | 2. | iron-sulphur protein |
| 3. | ferredoxin | 4. | quinone |
Lysozyme that is present in perspiration, saliva, and tears destroys:
| 1. | certain fungi | 2. | certain types of bacteria |
| 3. | all viruses | 4. | most virus-infected cells |
During the transmission of nerve impulses through a nerve fibre, the potential on the inner side of the plasma membrane has which type of electric charge?
| 1. | First negative, then positive, and again back to negative |
| 2. | First positive, then negative, and continue to be negative |
| 3. | First negative, then positive, and then continues to be positive |
| 4. | First positive, then negative, and again back to positive |
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