Science [5 marks Questions]

a. Iodised salt is advisable because Iodine present in iodised salt is essential for functioning of thyroid and formation of thyroxine hormone. The disease caused due to deficiency of iodine is Goitre. The symptom due to goitre is Swollen neck.
b. Nerve impulses travels from dendrite to cell body, then along the axon to its end. At the end, some chemicals are released which fill the gap of synapse, and starts a similar electrical impulse to another neuron and the impulse further travel in the body.

a. Two types of pollination are-
I. Self-pollination
II. Cross-pollination
Differences between the two are given below:-

Self-pollination	Cross-pollination
If the transfer of pollen occurs in the same flower, it is referred to as self-pollination.	The pollen is transferred from one flower to another, it is known as crosspollination.
It occurs in bisexual flowers.	It occurs in both bisexual and unisexual flowers.
It refers to the transfer of pollen grains from anther to stigma of the same flower or to another flower of the same plant.	It refers to the transfer of pollen grains from anther to stigma of flowers belonging to two different plants.
It is not necessary to use pollinators.	This transfer of pollen from one flower to another is achieved by agents like wind, water or animals.

b. The fusion of the female gamete (ovum or egg) and the male gamete created in the pollen tube by the pollen grains is known as fertilisation. The ovary transforms into the fruit after fertilisation, while the ovary wall transforms into the pericarp.
c. i. A: The young shoot of a plant embryo above the cotyledons is called a plumule. It is made up of the epicotyl and frequently immature leaves gives rise to mature shoot.
ii. B: In the course of germination, the radicle is the first component of a seedling to emerge from the seed. The plant's first root, known as a radicle, emerges from the soil downward give rise to future root system.
iii. C: The cotyledon is a crucial component of the embryo inside a plant seed. The cotyledon may develop into the seedling's first embryonic leaves after germination stored food.