Correct answer:
"<span>B- homologous chromosomes join together to form tetrads during prophase I"
</span>It is during prophase I that homologous chromosomes join together (<span>synapsis)</span> and form tetrads - four chromatids are together in the new structure of two chromosomes - and this is the reason why crossing-over occurs in this phase. It is in this tetrad that both arms of both chromosomes may crossover and matching regions exchange places. This process results in homologous chromosomes recombination leading to genetic variability.
Answer: a. Photo-periodism
Explanation:
The relative length of the day is considered as a major factor in the development of plants, particularly in sexual reproduction. The plants were grouped considering that the flowering and fruiting occurs only when the length of the day is within certain limits so that these phases are achieved only in certain times of the year. Therefore, some species respond to long days, while others respond to short days, and still, others are capable of responding to all day lengths. The name and meaning of each group became as follows:
Short Day Plants: They are the species that bloom in smaller photoperiods than a critical maximum.
Long day plants. These are the species that bloom in larger photoperiods than a critical minimum.
Neutral day plants: They are those that bloom in a wide range of the photoperiod.
Answer:
Contain a repair mechanism inherent in their biochemistry (repair enzymes)
Explanation:
When cells are exposed to sublethal doses of ionizing radiation, repair and recovery may occur because cells: Contain a repair mechanism inherent in their biochemistry (repair enzymes).
Answer:
Transcription & translation (Ans. A)
Explanation:
Prokaryotic organisms do not have membrane-bound organelles such as the nucleus, thus the process of transcription & translation occurs in the cytoplasm. Also because of the need for rapid life cycle, the mRNA molecules start to be made, & their ribosomes are ready to start making proteins more rapidly than Eukaryote, thus the process of the couple is quicker.
In eukaryotic organisms, transcription process start (happens) inside the nucleus of the cell and translation process can't start until the mRNA is transported out from the nucleus into the cytoplasm.
I think the answer is NUCLEUS.
Hope it helps!
