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जुलै १६, २०२३ पासूनच्या पोेस्ट दाखवत आहे

सुंदरता खरंच सुंदर असते का?

सुंदरता खरंच सुंदर असते का?  मुळात हा प्रश्नच खूप सुंदर आहे पण या मागे खूप साऱ्या विचित्र गोष्टी दडलेल्या आहेत.  हे आपल्याला कधीही कळणार नाही.  

write a short note on plasmids as cloning vectors.

Plasmids are small, extra -chromosomal, double stranded circular forms of  DNA that replicate autonomously. They are present in bacterial cells, yeast and animal cells. Plasmids are considered as replicons as they are capable of autonomous replication in suitable host. The most commonly used vectors in r-DNA technology are plasmids as they replicate in  E. Coli. Plasmid as a cloning vector should have a replication origin, a marker gene for antibiotic resistance, control elements like promoter, operator, ribosome binding site etc.and a region where foreign DNA can be inserted. Naturally plasmids do not have all these features. Hence, they are constructed by inserting gene for antibiotic resistance. Ti plasmid of agrobacterium tumefaciens is an important vector for carrying new DNA in many plants. It i up tself into the chromosomes of infected plant cells. The transposon, with the new DNA, can be inserted into the host cell's chromosomes. A plant cell containing this DNA, can t...

Write a brief account of ventricles in the brain.

Ventricles are the cavities present in different parts of the brain  There are four ventricles in the human 🧠.  All the ventricles are connected with each other. They are filled with cerebrospinal fluid. Paracoel or lateral ventricles -I and -II are present inside the cerebral hemispheres. The diencephalon has ventricle-III. Ventricle -III is in connection with lateral ventricles by foramen of Monro.

Phenotype and Genotype

Phenotype   Phenotype refers to the outward appearance of an individual such as shape, colour sex, etc. Phenotype can be observed directly in an individual. Individuals resembling each other may or may  not have the same Genotype. The phenotypic ratio obtained in the F 2 generation of a monohybrid cross is 3:1  Genotype Genotype refers to the genetic composition of an individual. Genotype cannot be seen, but can be found out by modern techniques like DNA  fingerprinting. Individuals prossessing the same Genotype usually have the same phenotypic expression. The Genotype ratio obtained in the F2 generation of a monohybrid cross is 1:2:1.

Give reasons: Loss biodiversity leads to the overall imbalance in the ecosystem.

The reason of imbalance of the ecosystem Loss of biodiversity in any area leads to the decline in plant production. There is lower resilience to environmental disturbance like flood. It may also lead to alteration in environmental processes like disease cycles plant productivity, etc. The food chains and food webs are disturbed. The productivity of the ecosystem is reduced and this results in overall imbalance in the ecosystem.

YAC,RE,dNTP,PCR

YAC -Yeast Artificial chromosome. RE - Restriction Endonuclease. dNTP - Deoxyribonucleoside triphosphates. PCR - Polymerase Chain Reaction.

Give reasons:Water is best transporting medium.

Water is in liquid state at room temperature. It is best solvent for most of the solutes. This called universal solvent. It is inert inorganic compound with neutral pH i.e.pH 7 when in pure form. Hence it is best medium for dissolved minerals.

Autogamy and Xenogamy

Autogamy (self-pollination) In self -pollination, bisexual flower is pollinated by it's own pollen grains. Self-pollination does not depend upon external agents for pollination. Self-pollination is economical as there is no wastage of pollen grains. Offspring are genetically similar to their parents; e.g. pea. Xenogamy (Cross-pollination) In class pollination the pollen grains from the anther  are carried to the stigma of another flower of same species. Cross pollination does depend upon external agents for pollination. Cross pollination is not economical as there is wastage of pollen grains during transfer. Offspring are genetically varied due to recombination. E.g..Food and fibre crops -Maize, Rice.