NCTB Class 8 Science Chapter 5 Co-ordination and Secretion Solution
Bangladesh Board Class 8 Science Solution Chapter 5 “Co-ordination and Secretion” Exercises Question and Answer by Experienced Teacher.
NCTB Solution Class 8 Chapter 5 “Co-ordination and Secretion”
|NCTB Bangladesh Board|
Co-ordination and Secretion
Short answer questions:-
(1) Importance of hormone: It helps in growth, it controls all the physic-chemical activity, etc.
(2) The function of auxin is it can induce adventitious roots in stem cutting and plays an important role in inhibiting the process of abscission of fruit.
The function of gibberellins is, due to its effect the internode of the plants elongates.
(3) Reflex action is the consequences of immediate action of nerve impulse, which occurs automatically without conscious though. It may be defined as the inborn, automatic actions of the body which are done without the involvement of thinking or brain.
(4) The function of kidney: It acts as filter, kidney extract harmful substance from blood, and excrete if from the body part of a liquid called urine.
Multiple choice questions:
(1) (c) Florigen – Helps flowering (blooming).
(2) (a) Kidney – Plays the key role in eliminating nitrogenous waste products.
(3) Proma’s money plant creep towards the windows because —- (c) Light.
(4) (d) (i), (ii), (iii) – Enhances the growth of Proma’s money plant.
(1) (a) Hormone is a organic compound which controls the growth, development of plant and animals.
(b) The role of auxin in plant are, it can induce adventitious roots in stem cutting and plays an important role in imhibing the process of abscission of fruit.
(c) The lower part of the cerebrum constitute the thalamus and hypothalamus which are the collection of neurones. So the above cell is located in lower part of the cerebrum.
(d) The above cell is very important in transmitting impulse in human body because it helps our body to maintain communications between internal and external environment of the body, coordinate the activities of different organ systems of the body, retain memory and to think and pass instruction for work.
(2) (a) The main excretory organ of human body is kidney.
(b) Due to sensitivity, effect of internal or external stimuli. On plant body creates sensation and consequently plant moves and grows. This type of movement is known as tropic movement.
(c) The structure that Apu was drawing is Neurone. It is the longest cell of human body. A typical neurone is divided into two parts, (a) Cell body (b) Processes cell body is the main part of neurone which is composed of cell membrane, cytoplasm and nucleus. The branch and tree like structure the extend from the cell body are called processes.
(d) Due to the reflex action. Apu caught Kanta’s hand. Which is related to the never system of Apu’s body after Kanta poked Apu, the sensory organ of Apu’s body is stimulated by the organ to the spinal cord through the afferent or sensory never fibres. In response, the central nervous system sends back a message through effect or to the muscle of the organ and Apu withdraw his hand and caught Kanta’s hand.