Question
One can sense colour only in bright light.

Answer

(i) The light sensitive screen of the eye called retina has two types of light sensitive cells.
(ii) Rod cells are concerned with vision in dim light and cone cells are responsible for the vision in presence of light.
(iii) Cone cells are also concerned with colour perception. They do not respond to dim light or no light
(iv) Thus, the knowledge of the colour is possible in presence of light and not in dark.
(v) Hence, we can identify and differentiate colours in presence of light.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

What are the objectives of the space mission?
Calculate the amount of energy that will be available to big fish in the following food chain, if 10,000 J of energy is available to small algae from the sun:
Small algae —> Zooplankton —> Fish —> Big fish
Obtain the mathematical expression for the heat generated in a metallic conductor by electric current (Joule’s law).
Observe the images below. Is it rational? Why?
Image
Can the following groups of elements be classified as Dobereiner's triads?
  1. Na, Si, Cl.
  2. Be, Mg, Ca.
Give reason for your answer.

(Atomic masses: Be 9; Na 23; Mg 24; Si 28; Cl 35. 5; Ca 40)
An element $X$ forms two oxides $XO$ and $XO_2$. The oxide XO has no action on litmus solution but oxide $XO_2$ turns litmus solution red.
  1. What is the nature of oxide $XO?$
  2. What is the nature of oxide $XO_2?$
  3. Would you call element $X$ a metal or a non-metal? Give reason for your choice.
  4. Can you give an example of element like $X?$ 
A food chain occurring in the sea which provides food for many people can be written as:
phytoplankton → zooplankton → X → Y
  1. Name one phytoplankton.
  2. Name two zooplanktons.
  3. What could be X?
  4. Name the organism which Y could be.
  5. Which organism in the above food chain is a (i) primary consumer, and (ii) tertiary consumer?
Whether the incidence shown in the following picture is rational? Express your opinion.
Image
The organisms A, B and C can obtain their food in three different ways. Organism A derives its food from the body of another living organism which is called its D, without killing it. The organism B takes in the solid food by the process of ingestion, digests a part of this food and throws out undigested food in the process called E. The organism C obtains its food from dead and decaying plants.
  1. What is the mode of nutrition of (i) organism A (ii) organism B, and (iii) organism C?
  2. What is the organism like D called?
  3. Name the process E.
  4. Give one example each of organisms like A, B and C.
  5. What is the general name of three modes of nutrition exhibited by organisms A, B and C?
Answer the questions based on Modern Periodic table.
Use your brain power;
ElementOBCNBeLi
Atomic radius(pm)66887774111152
Question
(i) By referring to the Modern Periodic table find out the period to which the above elements belong?
(ii) Arrange the above elements in a decreasing order of their atomic radii.
(iii) Does this arrangement match with the pattern of the second period of the Modern Periodic table.
(iv) Which of the above elements have the biggest and the smallest atom?
(v) What is the periodic trend observed in the variation of atomic radius while going from left to right within a period?