Practice Paper
TERM II (2021 – 2022)
Class – XI
Biology (044)
Time: 2 hours Maximum Marks: 35
General Instructions:
i) All questions are compulsory.
ii) The question paper has three sections and 13 questions. All questions are compulsory.
iii) Section–A has 6 questions of 2 marks each; Section–B has 6 questions of 3 marks each;
and Section–C has a case-based question of 5 marks.
iv) There is no overall choice. However, internal choices have been provided in some questions. A student has to attempt only one of the alternatives in such questions.
v) Wherever necessary, neat and properly labelled diagrams should be drawn.
SECTION – A
1. The following Statements describe the four main stages in the process of mitosis.
i) The spindle fibres break down and the nuclear membrane forms.
ii) The chromosomes arrange themselves on the equator of the cell.
iii) The spindle forms and the nuclear membrane disintegrate.
iv) The centromere splits and the sister chromatids migrate to the opposite poles of the cell.
Write the correct sequence of the stages in mitosis and also name each of the stage.
The correct sequence of the stages in mitosis is:
III (Prophase)—II (Metaphase)—– IV (Anaphase)—–I (Telophase)
2. In the diagram shown below, label A, B and C. Also mention what type of phosphorylation is possible in this?
The diagram is showing cyclic photophosphorylation. Here, A is electron acceptor, B is electron transport system and C is Photosystem-I or PS700. In cyclic photophosphorylation, PS-I is functional.
3. What would be the RQ value of yeast if it were to respire glucose anaerobically?
The RQ will be infinity during anaerobic respiration. In anaerobic respiration, CO2 is evolved, but oxygen is not used. Therefore, RQ in such case will be infinite.
Equation is as follows:
C6H12O6 → 2C2H5OH + 2CO2 + energy
RQ CO2/O2 = 2/0 = infinity
OR
Pyruvic acid generated in the crystal is transported to mitochondria and initiates the second phase of respiration. Before pyruvic acid enters the Kreb’s cycle, one of its three carbon atoms is oxidized to carbon dioxide in the reaction called oxidative decarboxylation.
(i) Name the enzyme that catalyses the process.
Pyruvate dehydrogenase
(ii) How many NADH is produced during this process
2 molecules of NADH are produced
4. (i) In an experiment, the callus produced from intermodal segments did not proliferate until coconut water was added. Give reason why?
Callus proliferates only when nutrient medium containing auxin was supplemented with coconut milk because it contains kinetin (a cytokinin which stimulated growth of plant tissues).
(ii) What would be expected to happen if- GA3 is applied to rice seedlings
Rice seedling will grow extremely tall.
5. Old people usually suffer from inflamed and stiff joints, name the condition. State the reasons for the symptoms.
It is called osteoporosis. It is an age-related disorder symbolized by diminishing bone mass and higher chances of fractures. In old-aged females, it is commonly caused due to decreasing levels in the estrogen hormones after menopause.
6. Name the gland that functions as a biological clock in our body where it is located? Name its one secretion.
The pineal gland functions as a biological clock because it regulates the circadian rhythms (sleep patterns) of the body. It is situated on the dorsal side of the forebrain. It secretes a hormone called melatonin.
OR
What is erythropoiesis? Which hormone stimulates it?
Formation of RBC is known as erythropoiesis and the hormone erythropoietin stimulates the process.
SECTION – B
7. Given below is the diagrammatic representation of a standard ECG. Label its different peaks.
If a patient’s ECG reveals an abnormally long delay between the P-wave and the QRS deflection, what does this suggest?
If a patients’ ECG revealed an abnormally long delay between P wave and the QRS deflection, it suggests that there is a delay of conduction from the atria to the ventricles, hence the stimulation from SA nodes are conducting stimuli very slowly to the ventricles.
8. Arrange the following terms based on their volumes in an ascending order. Write the volumes for each too.
a. Tidal Volume (TV)
Tidal Volume (TV): 500 mL
b. Residual Volume (RV)
Residual Volume (RV): 1100 mL-1200 mL
c. Inspiratory Reserve Volume (IRV)
Inspiratory Reserve Volume (IRV): 2500 mL-3000 mL
9. List the location in the cell where the following reactions take place during the process of photosynthesis.
a) Synthesis of NADPH and ATP
Outer side of the thylakoid membrane
b) Photolysis of water
The inner side of the thylakoid membrane
c) CO2 fixation
Stroma of chloroplast
10. Pyruvic acid is the end product of glycolysis. What are the three metabolic fates of pyruvic acid under aerobic and anaerobic conditions? Write in the space provided in the diagram.
(i) Under Aerobic condition: (CO2 + H2O) is formed.
(ii) Under anaerobic condition in our skeletal muscles (lactic acid) is formed.
(iii) Under anaerobic condition in yeast (ethyl alcohol + CO2) is produced.
11. A biology student asked his teacher that why two individuals of same population do not look similar.
The teacher told him about the concept of meiosis and crossing over. The teacher also mentioned that meiosis occurs in two stages which differ significantly.
(i) When does the crossing over occur in humans and name the type of cells involved in it?
Crossing over occurs during the pachytene stage of Prophase-I and Meiosis-I. It occurs in the reproductive cells of human body.
(ii) How many daughter cells are produced at the end of Meiosis-I and II respectively?
At the end of meiosis, I and meiosis II, two and four daughter cells are produced, respectively.
(iii) Draw diagrams to show the striking difference between Anaphase-I and Anaphase-II of meiosis.
12. Explain the factors on which the impulse conduction depends. What is the significance of Saltatory conduction?
Impulse conduction depends upon
(i) Permeability of axolemma ( axon Membrane)
(ii) Osmotic equilibrium between the axoplasm and extracellular fluid present outside the axon.
The process accounts for the greater speed of an impulse travelling along a myelinated neuron than along a non-myelinated on. It is upto 50 times faster than the non-myelinated nerve fibre.
OR
Observe the diagram and label A, B and C. Mention one function of each.
C. Synaptic vesicles are uniform organelles of ∼40 nm diameter that constitute the central organelle for neurotransmitter release.
B. A neurotransmitter is a signalling molecule secreted by a neuron to affect another cell across a synapse.
A. In postsynaptic cells, neurotransmitter receptors receive signals that trigger an electrical signal, by regulating the activity of ion channels.
SECTION – C
13. Observe the given diagram and answer the questions that follows:
(i) What is the role of the structure shown in the figure? Name it.
Malphigian body or renal corpuscle filter out large solutes from blood and delivers it small solutes to renal tubule for modification.
(ii) Label a, b, c and d.
Afferent arteriole, Efferent arteriole, Glomerulus, Bowman’s capsule, PCT
(iii) Give one point of difference between (a) and (b).
A brings blood to the Bowman’s capsule and B leave it to form Vasa recta.
(iv) Define podocytes (e).
Podocytes are cells in Bowman’s capsule in the kidneys that wrap around capillaries of the glomerulus. Podocytes make up the epithelial lining of Bowman’s capsule, the third layer through which filtration of blood takes place.
OR
Read the passage given below and answer the following questions given:
Kidneys are the chief excretory organs and are mainly concerned with the excretion of urea in the form of urine. They play a central role in cardiovascular homeostasis by ensuring a balance between the fluid taken in and that lost and excreted during everyday activities. This ensures stability of extracellular fluid volume and maintenance of normal levels of blood
pressure. Renal fluid handling is controlled via neural and humoral influences, with the former determining a rapid dynamic response to changing intake of sodium whereas the latter cause a slower longer-term modulation of sodium and water handling. The function of our kidney is monitored and regulated by the feedback mechanisms which involve the hypothalamus, juxta glomerular apparatus (JGA), and the heart.
(i) Name the hormone released by the heart for regulation of the kidney function.
Atrial Natriuretic Factor
(ii) How does Anti Diuretic Hormone (ADH) regulate body fluid volume?
The hypothalamus produces a polypeptide hormone known as antidiuretic hormone (ADH), which is transported to and released from the posterior pituitary gland. The principal action of ADH is to regulate the amount of water excreted by the kidneys. As ADH (which is also known as vasopressin) causes direct water reabsorption from the kidney tubules, salts and wastes are concentrated in what will eventually be excreted as urine. The hypothalamus controls the mechanisms of ADH secretion, either by regulating blood volume or the concentration of water in the blood.
(iii) Give the name of two actively transported substances in glomerular filtrate.
Glucose and Aminoacids.
(iv) State why the composition of glomerular filtrate is not the same as urine.
When the volume of the filtrate is compared with that of the urine that is formed per day, which is 180 litres and 1.5. Litres respectively, it can be extrapolated that 99% of the filtrate needs to be reabsorbed by the renal tubules, the phenomenon is referred to as reabsorption. Substances such as amino acids, Na+, glucose are actively reabsorbed in the filtrate hence are not found in urine.