Learn Unit II: World of Living with Free Lessons & Tips

• The small intestine in herbivores is larger than in carnivores primarily because plant matter requires more extensive digestion and absorption. Herbivores typically consume diets rich in complex carbohydrates like cellulose, which require longer processing times and more surface area for absorption. Therefore, a larger small intestine provides ample space for microbial fermentation and absorption of nutrients from plant material.

• A four-chambered heart provides efficient separation of oxygenated and deoxygenated blood, ensuring that oxygen-rich blood is pumped to the body tissues and oxygen-depleted blood is sent to the lungs for reoxygenation. This separation prevents mixing of oxygenated and deoxygenated blood, allowing for a more effective oxygen supply to the body tissues, which is particularly important for sustaining high metabolic rates in warm-blooded animals like mammals and birds.

• Inhalation in humans occurs through a process called negative pressure breathing. When the diaphragm and intercostal muscles contract, the volume of the thoracic cavity increases, causing a decrease in intra-thoracic pressure. As a result, air moves from an area of higher pressure (outside the body) to an area of lower pressure (inside the lungs), filling the lungs with fresh air.

The movement of leaves of the sensitive plant (Mimosa pudica) is known as thigmonasty and is triggered by touch or physical disturbance. In contrast, the movement of a shoot towards light, known as phototropism, is a directional response to light stimuli. Thigmonastic movement occurs rapidly and involves changes in turgor pressure within specialized cells, while phototropic movement occurs gradually and involves the differential growth of cells in response to light.

• Genetic drift is the random fluctuation in allele frequencies within a population due to chance events. It occurs more prominently in small populations where chance events can have a greater impact on allele frequencies. Genetic drift can lead to the loss of genetic diversity within a population over time.

• Genetic drift is the random fluctuation in allele frequencies within a population due to chance events. It occurs more prominently in small populations where chance events can have a greater impact on allele frequencies. Genetic drift can lead to the loss of genetic diversity within a population over time.

• Fossils have various uses, including providing evidence of past life forms, helping to reconstruct evolutionary history, dating geological formations, studying ancient climates and environments, and providing insights into the development of organisms and ecosystems over time.