List of top Biology Questions asked in CBSE Class XI

Find out what do the terms ‘algal bloom’ and ‘red-tides’ signify.

State two economically important uses of:

1. heterotrophic bacteria
2. archaebacteria

Distinguish between: 

1. afferent neurons and efferent neurons 
2. impulse conduction in a myelinated nerve fiber and unmyelinated nerve fiber 
3. cranial nerves and spinal nerves.

Differentiate between: 

1. Myelinated and non-myelinated axons 
2. Dendrites and axons 
3. Thalamus and Hypothalamus 
4. Cerebrum and Cerebellum

Explain the following processes:

1. Polarisation of the membrane of a nerve fiber
2. Depolarisation of the membrane of a nerve fiber
3. Transmission of a nerve impulse across a chemical synapse.

Give comparison between the following: 

1. C₃ and C₄ pathways 
2. Cyclic and non-cyclic photophosphorylation 
3. Anatomy of leaf in C₃ and C₄ plants

Figure 11.10 shows the effect of light on the rate of photosynthesis. Based on the graph, answer the following questions: 

1. At which point/s (A, B or C) in the curve is light a limiting factor? 
2. What could be the limiting factor/s in region A? 
3. What do C and D represent on the curve?

Draw labelled diagrams of the following: 

1. Neuron 
2. Brain

Briefly describe the structure of the Brain.

Discuss how classification systems have undergone several changes over a period of time?

Define and understand the following terms: 
(i) Phylum 
(ii) Class 
(iii) Family 
(iv) Order
(v) Genus.

Can you identify the correct sequence of taxonomical categories?
(a) Species → Order → Phylum → Kingdom
(b) Genus → Species → Order → Kingdom
(c) Species → Genus → Order → Phylum

Define a taxon. Give some examples of taxa at different hierarchical levels.

Given below is the scientific name of Mango. Identify the correctly written name. 
Mangifera Indica
Mangifera indica

What do we learn from identification of individuals and populations?

What different criteria would you choose to classify people that you meet often?

Draw the labelled diagram of the following: 
(i) gram seed 
(ii) V.S. of maize seed

Describe the various types of placentations found in flowering plants.

Draw illustrations to bring out the anatomical difference between (a) Monocot root and Dicot root (b) Monocot stem and Dicot stem

What is stomatal apparatus? Explain the structure of stomata with a labelled diagram.

Draw a neat diagram of digestive system of frog.

Name two cell-organelles that are double membrane bound. What are the characteristics of these two organelles? State their functions and draw labelled diagrams of both.

Describe the structure of the following with the help of labelled diagrams.
(i) Nucleus
(ii) Centrosome

Explain the composition of triglyceride.

Can you attempt building models of biomolecules using commercially available atomic models (Ball and Stick models).