Control and co ordination

Question 1

Explain progesterone and oestrogen

Answer 1

oestrogen are the changes during puberty like voice, skin etc..
progesterone uterine changes during menstrual cycle , helps in pregnancy

Question 2

What happens when insulin is not secreted in proper amounts

Answer 2

Insulin is secreted by pancreas
Sugar level rise - harmful effects for body

Question 3

Why is it necessary for us to have iodised salt in our food

Answer 3

Necessary for thyroid to make thyroxin hormone - regulates metabolism, fats etc… helps in balanced growth
Synthesises thyroxin hormone
suffer from goitre if deficient - swollen neck

Question 4

What happens in an emergency situation?

Answer 4

Adrenaline is secreted directly into the blood and carried to diff parts of body
mainly acts on heart which supplies more oxygen
The blood to the digestive system and skin is reduced to the contraction of muscles in small arteries
This diverts blood to skeletal muscles
Breathing rat increases due to contraction of diaphragm and rib muscles
All these responses help the animal to deal with a situation

Question 5

Chemical signals are sent throughout the body by a hormone…

Answer 5

Adrenaline secreted by adrenal gland
Hormone for emergency

Question 6

What are hormones

Answer 6

Hormones are minute, chemical messengers thrown into blood to act on target organs.

Question 7

Other plant hormones?

Answer 7

Gibberellins - help in growth of stem
Cytokinins - cell division present in seeds fruits
Absicisic acid - inhibits growth, wilting of leaves

Question 8

Explain auxin

Answer 8

Diff plant hormones help in coordinated growth, response etc…
These re synthesised away from where they act and are diffused at area of action
Auxin is a hormone in plant which helps plant growth by elongation this is synthesised at tip of cell
When is light is coming from one side auxin diffuses towards shady side and this helps the side of the shoot away from to light to grow longer - plant appears to bend towards light

Question 9

Chemical communication

Answer 9

Working by stimulated cells - releases some chemicals/hormones - diffuses around original cell
if other cells have special molecules to detect compound it can receive info and even transmit it

Question 10

Limitation to electrical impulse

Answer 10

Reaches cells only connected to nervous system
When an electrical impulse is generated it takes time to reset mechanism and generate new one

Question 11

What is directional movement explain in detail

Answer 11

Environmental triggers such as light gravity etcc changes the dir of the plant in which it grows in. These movs can be towards stimulus or away
Phototropism - response towards ligh - shoot grows towards light, roots bends away
Geotropism - response to pull of earth or gravity - vice versa
Chemotropism - growth of pollen tubes towards ovules
Hydrotropism - response to stimulus of water

Question 12

Why do plants appear as if its moving

Answer 12

Plants respond to stimuli slowly by growing in a particular direction. Since this growth is directional it appears to be moving

Question 13

Explain growth in pea plant

Answer 13

A pea plant uses tendrils and these tendrils are sensitive to touch. When they come in contact with the object the part of the tendril in contact with the object does ot grow rapidly as compared to the part of the tendril away from he object and this causes the tendril to circle around the object and cling to it.

Question 14

How do plants respond to stimuli?
How do plants and animals change shape differently?

Answer 14

The plants use electrical chemical means to convey information from cell to cell but there is no specialized tissue in plants for the conduction of information.
They also change shape by changing amt of water in them and this results in shrinking or swelling, unlike anils who have special proteins to change shape and arrangement in response to electrical impulse

Question 15

How does the nervous tissue cause action?

Answer 15

When a nerve impulse reaches the muscle the muscle fibre must move. The muscle cells will move by changing their shape so that they shorten. Muscle cells have special proteins that change both their shape and their arrangement in the cell in response to nervous electrical impulses. When this happens new arrangements of these proteins give the muscle cells a shorter form.

Question 16

Nervous system, nervous tissue, neurons and nerves

Answer 16

Nervous system is the organ system present in the animals to control and coordinate different activities of the body - brain spinal cord
Nervous tissue is made up of an organized network of nerve cells or neurons. It is specialized for conducting information via electrical impulses from one part of the body to another.
A neuron is the basic unit of the nervous system. Each neuron consists of three parts, namely, the cell body or cyton, branched projections called the dendrites, and the long process from the cell body, called the axon.
Nerve is a whitish fibre or bundle of fibres in the body made up of number of neuron cells that transmits impulses of sensation to the brain or spinal cord, and impulses from these to the muscles and organs.

Question 17

Types of nerve cells or neurons:

Answer 17

Sensory nerves send messages from the sense organs to the brain or spinal cord. • Motor nerves carry messages back from the brain or spinal cord to all the muscles and glands in the body. • Interneuron or relay neuron connects neuron within specific regions of the central nervous system. These are neither motor nor sensory.

Question 18

How are the tissues protected?

Answer 18

Human brain is protected by the thick bones of the skull and a fluid called cerebrospinal fluid which provides further shock absorption.
Vertebral column protects spinal cord

Question 19

Explain hind brain

Answer 19

Involuntary actions like bp, vomiting etc controlled by medulla in hind brain
Activities are possible due to cerebellum in hind brain –> responsible for precision of voluntary actions and maintaining posture and balance of body

Question 20

How are decisions made/ explain fore brain

Answer 20

The fore brain has regions which receive sensory impulses from receptors
Separate areas of association where the sensory information is interpreted by putting together info from other receptors and info already stored in brain
Based on this a decision is made on how to respond. This info is passed on to motor areas

Question 21

What are motor areas

Answer 21

Motor areas control the mov of voluntary muscles

Question 22

Which is the main coordinated centre of body…what are its 3 major parts

Answer 22

Brain
Fore Brain - Main thinking part of our brain, it has regions which receive sensory impulses from receptors, separate areas specialised for smell hearing etc…
Mid brain
Hind brain

Question 23

2 ways in which nervous system communicates with muscles

Answer 23

The motor neurons release a chemical, which is picked up by the muscle fibre. This tells the muscle fibre to contract, which makes the muscles move. Neurons carry messages from the brain via the spinal cord. These messages are carried to the muscles which tell the muscle fibre to contract, which makes the muscles move.

Question 24

Nervous action

Answer 24

Voluntary - action under our control
Reflex action - involuntary - immediate automatic
Involuntary - Action which not under our control

Question 25

What is synapse

Answer 25

Narrow gaps bw axon terminal of one neuron and dendrite terminal of another neuron
Electrical impulses changes from electrical to chemical back to electrical
Delivery of impulses from neurons to other cells

Question 26

Explain human nervous system

Answer 26

CNS
1. Brain
2. Spinal cord

Peripheral nervous system
1. connects brain and spinal cord to other organs of body

Question 27

Explain reflex arc and its components

Answer 27

Process of detecting a signal or input and responding so output can be quicker
Formed at spinal cord
Input goes to brain
It is evolved in animals thinking f brain not fast enough even tho nerve networks are complex
Components - spinal cord, sensory nerve response, stimulus receptor organ to effector organ (organ getting effected)

Question 28

Explain thinking tissue why does it take long to react

Answer 28

Made up of connected nerve cells which are intricately arranged
Acquires signals from nerves from all over our body
thinks about responding to them
Its a complex activity

Question 29

Explain the working of a nerve
What are receptors give examples

Answer 29

All information is detected by specialised tips called receptors. These are located in our sense organs. Eg - gustatory ( taste , olfactory (smell)
This information is acquired at the end of the dendritic tip of nerve cell and sets of chemical reaction which creates an electrical impulse. This travels from dendrite - cell body - axon - nerve end
Axon sets off same more chemicals. These chemicals cross a gap or synapse. The synapse finally allows the delivery of impulses from neurons to other cells.

Question 30

What is movement explain in brief (2m)

Answer 30

We associate movement with a change in environment of an organism
Also, a change in an env of an organism is taken for their advantage. Each change invokes a certain kind of movement or rather an event triggers it. These movements must be controlled and coordinated by specialised tissues