Transpiration is the process wherein water is lost from the plant body in the form of vapor. Role of transpiration: 1. Eliminates excess water. 2. Facilitates passive absorption of water and minerals. 3. Aids in the ascent of sap through transpiration pull. 4. Sustains cell turgor. 5. Provides a cooling effect by reducing temperature. 6. … Read more
Transpiration is the process in which water is lost in the form of vapor. Mechanism of closing and opening of stomata is as follows: Stomatal transpiration primarily involves minute pores. Stomata consist of two guard cells encircled by accessory cells. The opening and closing of stomata are regulated by the turgidity of guard cells. When … Read more
Theories of water translocation: The translocation of water is explained by various theories: 1. Vital force theories 2. Root pressure theory 3. Capillary force theory 4. Cohesion force theory Root pressure theory: Root pressure, once believed to drive water up plant stems, faces objections. The force is weak (max 2 atm), insufficient for tall trees. … Read more
A mechanism of water absorption: Water is absorbed through two mechanisms: active absorption and passive absorption. Active absorption: 1. Osmotic Active Absorption: This process involves water absorption through osmosis, where water moves into the root xylem against the concentration gradient of the root cell. The high concentration of solutes in the cell sap and the … Read more
Disruptive selection, also referred to as diversifying selection, occurs when genetic changes in a population favor extreme trait values rather than intermediate ones. This leads to an increase in the variation of the trait, causing the population to split into two distinct groups. Examples of disruptive selection include the beak size variation among Galapagos finches … Read more
1. Hugo de Vries found significant variations, with major changes linked to chromosomal issues and smaller changes to gene mutations. 2. Mutations happen slower than what’s needed for evolution to bring about significant transformations. 3. Chromosomal problems are unstable and often lead to sterile organisms, limiting their impact on evolution due to challenges in reproduction.
1. Fossils are the remains of ancient plants and animals found in different layers of the Earth. 2. The study of fossils gives us strong and direct proof of how evolution works. 3. Fossil studies show that life forms were not the same millions of years ago. 4. The geological timescale, which helps us understand … Read more
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The four major factors that are responsible for changing gene frequency are as follows: 1. Gene mutations :induce hereditary alterations either in a solitary gene or across an entire chromosome. 2. Natural selection:instigates modifications in the gene frequency within a population, subsequently fostering evolutionary changes over time. 3. Migration :engenders the relocation of populations, facilitating … Read more
Genetic drift is the random alteration of gene frequencies in a population due to chance, particularly prominent in small populations. 1. Founder effect occurs when a portion of the population, isolated or migrated, develops genetic distinctions from the original due to allelic frequency changes, potentially leading to the emergence of a new species. 2. The … Read more