Question

Write brief notes on the following:
(a) Photosystem II and photosystem I
(b) Budding
(c) Parthenocarpy
(d) Global warming
(e) Secondary air pollutants.

Answer 1

(a) Photosystem II is the first complex in the light-dependent reaction of photosynthesis. It is located in the thylakoid membrane. It contains chlorophyll a and chlorophyll b. Under normal conditions, electrons flow from PS II through cytochrome bf to PSI. Photosystem I absorbs photons of the wavelength of 700 nm. It provides high energy electrons to produce NADPH. Photosystem II absorbs photons of the wavelength of 680 nm.

(b) Budding is a type of asexual reproduction. In this, a new organism develops from a bud. The bud is developed due to cell division at one particular site. It occurs in both unicellular and multicellular organisms. For example, yeast, hydra.

(c) Parthenocarpy is the phenomenon in which the fruit develops without prior fertilization of ovule. This results in the seedless fruit formation. The fruit is a sterile fruit. It can be either natural process or can be induced artificially.

(d) Global warming is the phenomenon in which the average temperature of the Earth's climate increases. This results in many adverse effects. This results due to the greenhouse gases. Due to global warming, both land and oceans are warmer than earlier.

(e) Primary air pollutants are pollutants that are emitted directly from a source. Secondary air pollutants are not directly emitted but forms when primary pollutants react in the atmosphere. Examples of a secondary pollutant include ozone that is formed due to the combination of hydrocarbons and nitrogen oxides in the presence of sunlight and acid rain that is formed when sulfur dioxide or nitrogen oxides react with water.