Observe the illustration and answer the following questions. How impulses are generated in these cells when light rays fall on it?

Photoreceptors can be characterised as specialized cells that are found in the retina of the eye. The receptors of the eyes are extremely specialized neuroepithelial cells. There are two types of photoreceptors present in the eyes of the human. These are rod and cone cells. Cone cells help in colour vision. When light falls on cone cells, the photopsin in them dissociates into retinal and opsin. Rod cells help in dim light or low light vision. When light falls on rod cells, the pigment rhodopsin in them dissociates into retinal and opsin. This chemical change creates impulses and sends signals to the brain through the optic nerve for the processing of images.

Redraw the picture given below. Identify the name indicated and label the parts The part refracts light rays into the eye.

The human eyes play an essential role in the formation and processing of the image in the brain of the human. This sensory organ is composed of different parts. The transparent part in front of the sclera is called the cornea. The cornea refracts rays into the eyes.

Observe the illustration and answer the following questions. Explain the role of these cells in making vision possible.

Photoreceptors can be characterised as specialized cells that are found in the retina of the eye. The receptors of the eyes are extremely specialized neuroepithelial cells. There are two types of photoreceptors present in the eyes of the human. These are rod and cone cells. Cone cells help in colour vision. When light falls on cone cells, the photopsin in them dissociates into retinal and opsin. Rod cells help in dim light or low light vision. When light falls on rod cells, the pigment rhodopsin in them dissociates into retinal and opsin. This chemical change creates impulses and sends signals to the brain for the processing of images.

Observe the illustration and answer the following questions. Name the cells (A) and (B).

Photoreceptors can be characterised as specialized cells that are found in the retina of the eye. The receptors of the eyes are extremely specialized neuroepithelial cells. There are two types of photoreceptors present in the eyes of the human. These are rod and cone cells. In the given diagram A represents rod cells and B represents cone cells.

Redraw the picture given below. Identify the name indicated and label the parts The part of Retina where plenty of photoreceptors are seen.

Fovea centralis can be characterised as a small hole in the centre of the macula lutea. In the macula, the fovea centralis contains only cone cells. Macula means ‘spot’ and ‘lutea’ means yellow. Hence, it is also called a yellow spot. This is the part of retina where maximum photoreceptors are present. It is a highly pigmented and sensitive area on the centre of the retina. The yellow colour of macula lutea is due to the presence of a yellow pigment known as macular pigment.

Observe the given steps related to the experience of taste and arrange them properly. Impulses reach the brain through the nerves. The taste detecting chemoreceptors are stimulated. The substances reach the taste buds through saliva. Substances responsible for taste dissolves in saliva. Forms the experience of taste. Impulses form in the chemical receptors.

Taste can be characterised as a physiological process by which we can know the nature of the food. At first, we intake the food and the foods are broken into pieces by teeth and lubricated by saliva. The tongue facilitates the process of mixing food with saliva. The food particles are sensed by the taste buds. Then the chemoreceptors get stimulated and the impulses for the taste are carried by the glossopharyngeal nerve. This nerve carries the impulse to the brain. After the processing of impulses, the individual can experience the taste of the food. The steps are arranged and given below: Substances responsible for taste dissolve in saliva. The substance reaches the taste buds through saliva. The taste detecting chemoreceptors are stimulated. Impulses form in the chemical receptors. Impulses reach the brain through the nerves. Forms the experience of taste.

EASY

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State the difference between the two:-

Iris and Pupil

Important Questions on Nervous System

EASY

Science>Biology>Nervous System>Sense Organs

Fill the blanks in the statement.
"Three types of cone cells are present in human eye. This is due to the chänge in _____ in the Opsin molecule"

MEDIUM

Science>Biology>Nervous System>Sense Organs

Why is chemical communication better than electrical impulses as a means of communication between cells in a multi-cellular organism?

HARD

Science>Biology>Nervous System>Sense Organs

Give the biological reasons for the following statement:
We cannot distinguish colours in dim light.

EASY

Science>Biology>Nervous System>Sense Organs

Membranous labyrinth in the inner ear is filled with perilymph.

MEDIUM

Science>Biology>Nervous System>Sense Organs

Write one function of lens of the human eyeball.

EASY

Science>Biology>Nervous System>Sense Organs

Observe the illustration and answer the following questions.

Question Image

How impulses are generated in these cells when light rays fall on it?

MEDIUM

Science>Biology>Nervous System>Sense Organs

Choose between the two options to answer the question specified in the brackets for the following.

An example is illustrated below.

Example: Corolla or Calyx (Which is the miter whorl?) Answer: Calyx

Perilymph or endolymph (Which one surrounds the organ of Corti?)

MEDIUM

Science>Biology>Nervous System>Sense Organs

The process that leads to the formation of impulses in photoreceptors is :

MEDIUM

Science>Biology>Nervous System>Sense Organs

Write one function of Iris of the human eyeball.

EASY

Science>Biology>Nervous System>Sense Organs

Redraw the picture given below. Identify the name indicated and label the parts

Question Image

The part refracts light rays into the eye.

EASY

Science>Biology>Nervous System>Sense Organs

Observe the illustration and answer the following questions.

Question Image

Explain the role of these cells in making vision possible.

EASY

Science>Biology>Nervous System>Sense Organs

Vitreous humor is formed from blood, and is reabsorbed by blood.

EASY

Science>Biology>Nervous System>Sense Organs

Observe the illustration and answer the following questions.

Question Image

Name the cells (A) and (B).

MEDIUM

Science>Biology>Nervous System>Sense Organs

What is the function of receptors in our body? What problems can originate when receptors do not work?

EASY

Science>Biology>Nervous System>Sense Organs

Acharya Jagadish Chandra Bose proved the property of _____ by sending electrical impulse in Mimosa and Desmodium plant. (stimulation of leaf movement/ stimulation of stem movement)

EASY

Science>Biology>Nervous System>Sense Organs

Redraw the picture given below. Identify the name indicated and label the parts

Question Image