Solved Board Paper For CBSE Class 11 Biology

Option (a): Mango

Explanation: Mangifera indica is the binomial nomenclature of mango. The first part represents the generic name (Mangifera), while the last part represents the specific epithet(indica).

Option (d):Protista

Explanation: Protistans are eukaryotic unicellular organisms. They live in solitary as well as in a colony. They have a nuclear membrane and mitochondria.

Option (c): Fallopian tubes and bronchioles

Explanation: Ciliated epithelium is present mainly in hollow organs like fallopian tubes and bronchioles. Its main function is to move particles or fluid in a specific direction over the epithelium.

Option (b): Lymphocytes

Explanation: Lymphocytes are one of the main types of immune cells. Lymphocytes are of two types, namely B and T cells. B lymphocytes produce antibodies.

Option (b): i- Pachytene, ii- Diplotene, iii- Leptotene, iv- Zygotene

Explanation: In prophase I of meiosis-I, the following events take place:

• Condensation of nuclear chromatin takes place in leptotene.
• Pairing of homologous chromosomes takes place in zygotene.
• Terminalization of chromosomes takes place in diplotene.
• Crossing over takes place in pachytene.

Option (d): Sulphur

Explanation: Sulphur is a macronutrient that is required by plants in large quantities. Its deficiency results in chlorosis, which appears first in young leaves.

Option (c): A=12, B=7, C=3

Explanation: Humans have 12 pairs of ribs. The first seven pairs of ribs are called true ribs. The 8th, 9th, and 10th pairs are called false ribs. They do not directly connect with the sternum but join the seventh rib with the help of hyaline cartilage.

a) The companion cells help to maintain the pressure gradient in the sieve tubes.

b) The trichomes prevent water loss due to transpiration.

The two roles of fungi are:

i) Fungi, like Agaricus, are used as food.

ii) Yeasts are used in the fermentation process.

a) Direct development

b) Indirect development

The endosperm of angiosperms is triploid due to the process of triple fusion, whereas the endosperm of gymnosperms is haploid.

No. of cells initially in the beaker =1

After 1 minute number of cells will be 2×1=2¹

After 2 minutes number of cells will be =2×2=2²

After 3 minutes number of cells will be =2×2×2=2³

So, after 60 minutes number of cells will be 2^60

Quantity of whole beaker =2^60 cells

Quantity of half a beaker =2^60/2=2^59

Thus, time taken to fill half of the beaker =118 minutes.

Alcohol is diuretic and decreases the secretion of ADH. This in turn, lowers the water reabsorption and increases the urine output.

Respiratory quotient (RQ): It refers to the ratio of the volume of carbon dioxide released to the volume of oxygen consumed during respiration in a given period of time at a standard temperature and pressure.

Tripalmitin is a fatty acid. The chemical formula of tripalmitin is C₅₁H₉₈O₆.

2(C₅₁H₉₈O₆) + 145O₂ →102CO₂ + 98H₂O + Energy

Thus, RQ = 102CO₂/145O₂ = 0.7

a)

b)

a) Mitochondria are known as the power house of cell because they have the functionality to synthesise ATP molecules, the energy currency of the cell. This energy is utilised for all the cellular activities.

b) Kolliker was the scientist that discovered this semi-autonomous organelle.

a) Multicellular organisms are made up of different cells. All these cells are specialised in their structure to perform their specific functions. These cells together form different types of tissues, which further coordinate to form organs and organ systems. Each organ system has a specific function and they all work in coordination. This increases the working efficiency and the chances of survival in multicellular organisms.

b) The object is magnified as it gives a clear and bigger image of the object. It also helps us to study the detailed structure of an object

a) Cyathium: It is a special type of inflorescence present in the flowers that are naked and without perianth. The male flower is single stalked stamen and the female flower is single stalked pistil. The group of flowers is surrounded by a cup-like structure (involucre), which is formed by the fusion of bracts. Example, Euphorbia.

b) Spadix: It is a type of racemose inflorescence. It is a modification of spike, has thick and fleshy peduncle, which may be coloured on the upper side. It has small, sessile flowers borne on a fleshy stem. The whole is usually being surrounded by a spathe. Example, Colocasia.

c) Cymose: It is a type of inflorescence, in which the main axis terminates in a flower, hence is limited in growth. The flowers are borne in a basipetal order. Example, Drosera.

a) The graph indicates the presence of an enzyme inhibitor in the reaction mixture. Enzyme inhibitors are those substances which interfere with the catalytic action of the enzyme and subsequently slow down, or in some situations, stop catalysis.

b) The graph indicates that the enzyme becomes temporarily inactive. Each enzyme shows its highest activity at a particular temperature, called optimum temperature. The enzyme activity declines both below and above the optimum level. When the temperature is lower than the optimum level, the enzymes become temporarily inactive.

a) Photoperiodism refers to the physiological reaction of plants to the relative length of light and dark periods with regard to the initiation of flowering.

b) The given plant should be placed in long day plant category. These plants require a short period of darkness. They flower when the day length exceeds a critical length. They may flower even if a flash of light is given to them during a dark period

c) Flowering will take place in both the set-ups. Rose being a day neutral plant is not affected by photoperiod. It flowers irrespective of the light duration at its maturity. Hence, in both cases, the plants will bear flowers as they are mature.

RuBisCo is an enzyme that is used by C₃ (Calvin cycle) and C₄ plants. It combines with carbon dioxide (CO₂) and helps in its fixation, thereby helping in photosynthesis.

RUBP Carboxylase-Oxygenase is considered to be a more appropriate name for RuBisCo. This is because this enzyme can function as both carboxylase and oxygenase under different carbon dioxide and oxygen ratios.

a) Arteries are the blood vessels that carry blood away from the heart. In arteries, blood flows with high pressure, therefore their walls are thick. On the other hand, veins carry blood from different body parts to the heart. Since blood in veins flows with less pressure, their walls are not as thick as the walls of arteries.

b) The left ventricle of our heart has the thickest wall because the left ventricle sends oxygenated blood to all the body parts, so it has to exert more force to pump the blood all over the body.

c) Blood group ‘O’ is called the universal donor as it does not have antigens, so it can be transfused to all the recipients.

a) maltose

b) trypsin

c) glycerol

d) duodenum

e) bile juice

f) pancreatic juice

Family-Solanaceae

Floral Diagram

Floral Formula

a) ABA (Abscisic acid) is called the stress hormone. It is called so because this hormone increases the tolerance of plants and induces various responses in them towards stress conditions.

b) ABA helps to overcome stress conditions by stomatal closure. During water stress, it leads to closure of stomata. It also induces seed and bud dormancy.

c) The formation of ABA occurs in the chloroplasts of leaves.

a) The blue bar of the graph is depicting the percentage of components of inspired air, while the red bar is depicting the percentage of components of expired air.

b) When we inhale, cells of our body utilise only oxygen present in the blood to release energy. Due to this, the concentration of oxygen becomes lower in the blood that is returning to the lungs as compared to the blood that is leaving the lungs. Hence, its percentage drops down to 18% in the expired air.

c) Oxygen is transported to various tissues in the body by haemoglobin in the form of oxyhaemoglobin. When oxyhemoglobin reaches the tissue where carbon dioxide concentration is high, oxygen is released and carbon dioxide is loaded onto the haemoglobin.

As per IUB system of classification, enzymes are divided into following six classes on the basis of the type of reaction they catalyse:

1. Oxidoreductases
2. Transferases
3. Hydrolases
4. Lyases
5. Isomerases
6. Ligases

Lyases: These enzymes catalyse the cleavage of specific covalent bonds and the removal of groups without hydrolysis. They act on C-C, C-N, C-O, C-S and C-halide bonds. For example: decarboxylases remove carbon dioxide.

Isomerases: These enzymes catalyse the rearrangement of the molecular structure to form isomers. For example glucose isomerase.

Interphase is the interval period between two successive cell divisions. It is a resting stage, but actually a period of diverse activities. Interphase is basically a preparatory phase, in which a cell prepares itself for next cell division. It is a metabolically active phase as a cell undergoes a number of biosynthetic activities. It lasts for more than 95% of the duration of the cell cycle.

Interphase is divided into the following three sub-phases:

1. G₁ Phase
2. S Phase
3. G₂ Phase

G₁ Phase: It is also known as post-mitotic gap phase. It involves the synthesis of structural and functional proteins.

S Phase: It is also known as the synthesis phase. It lasts for 6-8 hours. In this phase, DNA replication takes place.

G₂ Phase: It is also known as the pre-mitotic phase. It lasts for 2-5 hours. In this phase, the cell prepares itself for mitosis. Cell continues to grow and synthesise new proteins and RNA during the G₂ phase.

a) Aerobic respiration is considered to be more efficient as compared to anaerobic respiration because it releases more energy. Energy is released in the form of ATP. During aerobic respiration, one glucose molecule is oxidised to release 36 molecules of ATP. On the other hand during anaerobic respiration, only 2 molecules of ATP are released for every glucose molecule.

b) Red blood muscle fibres in animals contain myoglobin as the respiratory pigment. Plenty of oxygen can be stored and transported by this pigment. This is why red muscle fibres in animals can work continuously for longer time periods.

c) Many compounds formed during the respiratory pathway are withdrawn for the formation of various substrates. For example, acetyl CoA is linked for fatty acid formation; many respiratory intermediates are withdrawn for protein formation, etc. This is why; respiration is an amphibolic pathway.

a) Excess manganese slows down the solubility of other cations. High concentration of manganese reduces iron and magnesium uptake and stops the movement of calcium to the tips of the stem.

Some measures that can prevent such deficiencies are:

1. Manganese should not be added.
2. Deep drains should be dug on the sides of the fields.
3. Watering should be done to drain excess manganese.

b) Hydroponics requires technical expertise and a high cost for infrastructure. Also, chemicals used for the preparation of nutrient solutions may have various toxic substances. Hence, most crops are grown on land, although hydroponics is a successful technique for plant growth.

(a)

(b) The retina contains photoreceptor cells called rod cells and cone cells. The photoreceptor cells contain light-sensitive photopigments that are composed of opsin (a protein) and retinal (an aldehyde of vitamin A). When light falls on the retina passing through the pupil, it causes dissociation of retinal from opsin. This causes the changes in the conformation of opsin resulting in a change in membrane permeability of photoreceptor cells and generation of the action potential. These impulses are transmitted by the optic nerves to the visual cortex area of the brain, where the neural impulses are analysed and the image formed on the retina is perceived.

a) The endocrine gland affected in this case is pancreas.

b) The hormones released from the pancreas are insulin and glucagon.

c) Functions of insulin:

• It stimulates the transport of glucose from the blood to muscles and adipose cells.
• It promotes the conversion of glucose into glycogen in muscles and liver cells.

Functions of glucagon:

• It accelerates the breakdown of glycogen into glucose in the liver.
• It enhances the release of glucose into the blood.

d) When we consume food, the glucose level increases in the blood. This increase in blood glucose level stimulates the beta cells of islets of Langerhans in the pancreas to secrete insulin hormone. The release of insulin decreases the level of glucose in the blood by stimulating target cells to take up glucose from the blood. This decrease in the blood glucose level stimulates the pancreas to secrete glucagon hormone in the blood. Glucagon stimulates the breakdown of glycogen into the glucose in the blood. As a result, the blood glucose level increases again. Thus, insulin and glucagon work antagonistically to keep the blood sugar level balanced.