BIOLOGY 3 Marks Question

i. It is representing impulse conduction through an axon.
ii. Na moves inside the membrane and polarity of the membrane is reversed at point A.
iii. The potential difference at point A is known as the action potential.

Hypertension is another name for high blood pressure which is the force exerted by the blood against the walls of the blood vessels. The pressure depends on the work being done by the heart and the resistance of the blood vessels.
Some of its Causative factors are:
i. Age: The risk of high blood pressure increases as a person becomes older because the blood vessels become less flexible.
ii. Ethnic background: African-American people have a higher risk of developing hypertension than other people. Hypertens also presents more severely in African-American people and is less responsive to certain medications.
iii. Obesity and being overweight: People who are overweight or have obesity are more likely to develop high blood pressure.

The normal activities of the heart are intrinsically regulated, i.e., autoregulated by the specialised muscles, (nodal tissue). Thus, the heart is known as a myogenic heart.
The neurogenic heartbeat is initiated by a nerve impulse, e.g., annelids and most arthropods.
The rate of its formation and conduction is regulated by the following
i. Neural Regulation: In medulla oblongata, a special neural centre is present, which can moderate, the cardiac function thro the Autonomic Nervous System (ANS).
ii. Hormonal Regulation: Adrenaline and noradrenaline hormones secreted by the medulla of adrenal gland has a significant role in regulating heartbeat and thus increasing the cardiac output. The noradrenaline accelerates the heartbeat, while adrenaline does this function at the time of emergency

1. The different parts of cranial bones are as follows:
1. A-FRONTAL
2. B-PARIETAL
3. C-TEMPORAL
4. D-OCCIPITAL
5. Ε-ΕΤΗΜOID
2. The mandible is the only movable bone in the skull of the man.
3. On the basis of the presence or absence of a red pigment called myoglobin, the skeletal muscles are classified into red and white muscles.

i. A bioassay means "the evaluation of the effect of a substance on a living organism under controlled conditions. "Two bioassays used to examine auxin activity in plants are the following:
a. The avena Curvature Test and
b. Root Growth Inhibition Test.
ii. Abscisic acid (ABA): It is a phytohormone that acts antagonist to gibberellins. Gibberellin was initially extracted from the fungus named Gibberella fujikuroi. Two bioassays of this growth hormone are the following:
a. Shoot elongation is some dwarf stems and
b. Barley Endosperm test.

The amphibians are adapted to dual/ double mode of life that is on land as well as in water called amphibians animals. Adults move on land by the limbs and breath by lungs. There are no marine forms. Aquatic forms e.g. Newt and Salamanders have gills. Frogs and toads are terrestrial. Toad occurs on dry land but the frog is found near water in marshy zones. Tree frogs like Hyla and Rhacophorus are arboreal (live on the trees). They do not have a tail but adhesive discs on toes and web, frog produces in water.

Bryophytes commonly grow in moist, shaded areas in hills. These are also called amphibians of the plant kingdom because, these can live in soil, but are dependent on water for sexual reproduction.
Some bryophytes grow in diverse habitats, such as
i. Aquatic, e.g. Riccia, Ricciocarpus, Riella
ii. Epiphyte, e.g. Radula, Dendroceros
iii. Saprophyte, e.g. Buxbaumia, Cryptothalius
iv. Dry habitats, e.g. Polytrichum
v. Deserts, e.g., Tortula desertorum
vi. Dry rocks, e.g., Porella