In a cross between a homozygous dominant plant (TT) and a heterozygous plant (Tt), what proportion of the offspring will show the recessive phenotype? MCQ with Answer and Explanation

Explanation:
P700 is the reaction center chlorophyll a of photosystem I, absorbing light at 700 nm. It donates electrons to ferredoxin. P680 is the reaction center of PSII. Chlorophyll b and carotenoids are accessory pigments. The two photosystems work in series to transfer electrons from water to NADP⁺.

Explanation:
In roots, the protoxylem (first formed xylem) lies towards the periphery and metaxylem towards the centre; this arrangement is called exarch. In stems, protoxylem is towards the centre, called endarch. Exarch condition is typical of roots. Mesarch is found in ferns. This arrangement aids in understanding anatomical differences between root and stem.

Explanation:
A reflex arc is the neural pathway that controls a reflex action. It typically involves: a receptor (detects stimulus), a sensory neuron (carries impulse to CNS), an interneuron (in the spinal cord), a motor neuron (carries impulse away from CNS), and an effector organ (muscle or gland that responds). The motor neuron is responsible for the final output.