Biology
Briefly explain the following terms:
(i) Genes.
(ii) Cytokinesis in plant cells.
(iii) Guttation.
(iv) Diabetes insipidus.
(v) Disinfectants.
Answer
(i) Genes are specific sequences of nucleotides on a chromosome that encode particular proteins which express in the form of some particular feature of the body. They are the units of heredity which are transferred from parents to offsprings and are responsible for some specific characteristics of the offspring.
(ii) Cytokinesis is the division of cytoplasm. In plant cells, a cell plate appearing at the centre of the middle grows up to the periphery, splitting the cytoplasm into two and thus producing two new cells.
(iii) Guttation is the process by which drops of water appear along leaf margins due to excessive root pressure. It occurs early mornings or late nights.
(iv) Deficiency of Vasopressin (Anti-diuretic hormone or ADH) causes Diabetes Insipidus in which urination is frequent and copious, resulting in loss of water from the body and the person becomes thirsty.
(v) These are the chemicals that kill microbes once they come in contact with them, they are too strong to be used on the body. Example — Phenol and Cresol.
Related Questions
The figure given below shows the epidermal cells of an onion bulb. This cell was then transferred to a drop of sugar solution.
(i) Draw a well labelled diagram of the epidermal cell as it would appear after immersion in a strong sugar solution.
(ii) What scientific term is used for the changes as shown in (i) above ?
(iii) What should be done to restore the cell back to its original condition ?
(iv) Give the scientific term for the recovery of the cell as a result of the step taken in (iii) above.
(v) Define the term osmosis.
(i) List any two major activities of the Red Cross.
(ii) Write any two major reasons for the population explosion in the world.
(iii) Write the names of four nitrogenous bases in a DNA molecule.
Give biological reasons for the following :
The hand automatically shows the direction to turn a cycle without thinking.
(i) Draw a well labelled diagram to show the anaphase stage of mitosis in a plant cell having four chromosomes.
(ii) State any two harmful effects of acid rain.
(iii) Expand the following biological abbreviations :
- NADP
- ACT