Explanation: Plant fertilization, the types are: Porogamy: Fertilization occurs through the micropyle (the opening of the ovule). Chalazogamy: Fertilization occurs through the chalaza (the base of the ovule). Mesogamy: Fertilization occurs through the middle of the ovule. Gynogamy is not a recognized type of fertilization in plants.

Explanation: T-cells are primarily involved in cell-mediated immunity. They play a crucial role in recognizing and responding to infected cells, cancer cells, and foreign pathogens. B-cells, on the other hand, are mainly involved in humoral immunity, which involves the production of antibodies to neutralize pathogens. Mast cells are involved in allergic responses and do not play a direct role in cell-mediated immunity.

Explanation: Phosphorus is the chemical fertilizer needed for better rhizobial nitrogen fixation. Phosphorus is essential for the development and functioning of the rhizobium bacteria in legumes, which are responsible for fixing atmospheric nitrogen into a form usable by plants. Adequate phosphorus helps enhance the efficiency of this process, leading to improved plant growth and yield.

Explanation: An adult human has 4 canine teeth. These are located in the upper and lower jaws, with one canine tooth on each side of the mouth, both in the upper and lower jaws. An adult human typically has 32 teeth, including the canines. Canines, also known as cuspids, are located at the corners of the dental arches. They play a crucial role in tearing food due to their sharp, pointed edges. There are four canine teeth in total: two in the upper jaw and two in the lower jaw.

Explanation: Tropism refers to the growth movement of a plant in response to an environmental stimulus. Here's a brief summary: Phototropism: Growth response to light. Stems typically exhibit positive phototropism (grow towards light), while roots often show negative phototropism (grow away from light). Geotropism (or gravitropism): Growth response to gravity. Roots generally exhibit positive geotropism (grow towards gravity), while stems show negative geotropism (grow away from gravity). These tropic responses help plants optimize their exposure to light and nutrients.

Explanation: In a collateral vascular bundle, the xylem and phloem are arranged side by side along the same radius. The xylem is typically positioned towards the inner side (central axis), while the phloem is on the outer side. This arrangement can be classified as either open (where there is a cambium layer between xylem and phloem allowing for secondary growth) or closed (without a cambium layer). The term "collateral" is also synonymous with "conjoint" in this context.