Model Question Paper

Systematics is the branch of biology that deals with an organism’s classification, nomenclature and overall taxonomy.

It plays a crucial role in biology. It provides a means for characterizing of organisms that need to be studied. Systematics also allows scientists to study evolutionary relationships.

Carl Linnaeus is know are the father of Systematics.

Venation describes the pattern of arrangement of veins and veinlets in a lamina.

There are two types of venations:

1. Reticulate venation

2. Parallel venation

Reticulate venation: Net-like pattern of veins arrangement.

Parallel venation: Small veins run parallel to each other.

The cambium that arises between the vascular bundles in the stem of a plant is known as the interfascicular cambium.

Cork cambium is the cambium tissue in the stem of a plant that gives rise to the cork on its outer surface. It is the lateral meristem and is responsible for secondary growth, replacing the epidermis in roots and stem.

Both, interfascicular cambium and cork cambium are formed due to cell dedifferentiation. Differentiation is the process which causes maturation of cells.

Dedifferentiation is the process in which a differentiated cell regains its ability to undergo cell division again under certain conditions.

A connective tissue is one of the four major types of tissue found in animals. It has mesodermic origin i.e. it develops form the mesoderm.

Blood, bone and cartilage are connective tissues while muscle isn’t.

Blood: Transports oxygen and other important substances within the body.

Cartilage: Provides strong support and connection to the skeletal framework.

Bones: Support and protect soft tissues and oragns of the body.

In secretory cells, the rough endoplasmic reticulum is observed easily in the cell. Secretory cells are actively involved in the process of protein synthesis and secretion. They have both Rough and Smooth Endoplasmic Reticulum. No secretory granules are found in the nucleus.

A zwitterion is any molecule or ion that has both positively and negatively charged groups. It is also called a dipolar ion. They have an overall neutral charge.

In case of meiosis that is our reduction division, cell division happens twice.

Meiosis 1 has four stages:

1. Prophase 1

2. Metaphase 1

3. Anaphase 1

4. Telophase 1.

It is during Anaphase 1 that the homologous chromosomes separate. Anaphase 1 begins when the two chromosomes of the bivalent tetrad separate and start moving towards opposite poles of the cell.

The form of sugar transported through phloem is sucrose.

The process of this transportation is known as pressure flow. In this mechanism, sucrose is transported from the source to the sink. The source is usually the leaves. The sugars from source move through the sieve elements via active transport.

The statement D here is false since nitrogen fixing microbes aren’t photoautotrophs but chemoautotrophs.

They do not use sunlight to manufacture their food but instead oxidize inorganic substances and utilized the energy released. Moreover, these bacteria also aid in the conversion of ammonia to usable forms of nitrogen.

PEP stands for Phosphoenolpyruvate. It is the primary carbon dioxide acceptor in C4 plants. It is found in the mesophyll cell cytoplasm of C4 plants. The CO₂ acceptor in case of C3 plants os RuBP i.e. Ribulose-1,5-bisphosphate.

Glycogen is a multibranched polysaccharide or a homopolymer of glucose. It serves as an energy reserve in case of animals, bacteria and even fungi. It is the primary form of glucose storage.

Glycogen accumulates in response to the insulin breakdown. It is mainly stored in the liver and muscles. Its function is to provide the body with a readily available source of energy in case the blood glucose level goes down.

Dengue is a disease caused by the dengue virus which is carried by the Aedes mosquito. In a person with dengue, the platlet count drastically decreases. The normal count of platelets is 1.5 lakh to 4.5 lakh per microlitre of blood. In dengue, this count goes down to 20,000 or even lower.

The incorrect statement is B.

The reason being that the region extending between the medullary pyramids is known as Column of Bertin →or Renal colimn) and NOT renal pelvis. The renal pelvis is the upper enlarged end of the ureter.

The hormones responsible for her restlessness are: Adrenaline and noradrenaline. Together, these two hormones produce the fight or flight effect. They are released in response to a stressful situation. They are released in the bloodstream and cause an increase in blood pressure, increased heart rate and blood sugar levels.

The organism will be identified to be a Dinoflagellate given the characteristics.

Dinoflagellates are protists. They are unicellular, motile and planktonic. Some dinoflagellates are photosynthetic.

They have two dissimilar flagella. They are constructed in a different way and move in different ways. One lies longitudinally and the

other transversely in a furrow between the wall plates.

The phylum exhibiting the said criteria is the phylum Echinodermata. These are invertebrate that are characetrised by having a hard and spiny covering. The adults show radial symmetry while the larva exhibit bilateral symmetry.

It is the male frog in which sound producing vocal sacs are present. The vocal sacs are a flexible membrane of skin. It is found in males for the purpose of making mating sounds or calls to the females. When male frogs call, their throat region usually expands as their vocal sac fills with air, amplifying their call.

Depending on the position of the centromere, the chromosomes are of the following type:

1. Metacentric

2. Sub-metacentric

3. Acrocentric

4. Telocentric

In case of metacentric chromosomes, the centromere is present in the middle of the two arms of the chromosomes in such a way that the two arms are equal in length.

A reduced + A’ oxidized → A oxidized + A’ reduced

Reason: Oxidoreductase enzyme catalyzes the electron transfer from one molecule →the reductant or the electron donor) to another molecule →the oxidant or electron acceptor)

In the given scenario, the plant dies because of exosmosis. Due to the addition of urea, the medium became hypertonic as a result of which the plant cell began losing water.

II – Antiport

III- Symport

Both symport and antiports are involved with active transport in plants.

Antiports transport molecules in opposite directions while symports transport molecules in the same direction.

NADP reductase is found in the stroma side of the thylakoid membrane.

Function: NADP reductase enzyme helps in the reduction of NADP⁺ to NADPH + H⁺ creating a proton gradient across the thylakoid membrane which leads to energy release.

Cigarette smoking is injurious to health. It damages the alveolar walls and decreases the surface area for gaseous exchange. In emphysema, the air sacs i.e. the alveoli get damaged and the body doesn’t get the oxygen that it needs. Emphysema is a chronic obstructive pulmonary disease.

The correct order is: Ear drum → Malleus → Incus → Stapes → Cochlea → Cochlear nerve

• Sound waves enter the ear, travel through the outer ear, enter the external auditory canal and strike the ear drum and make it vibrate.

• The central part of the ear drum is connected the malleus →found in the middle ear.) The malleus vibrates and transmits the vibrations to incus and stapes.

• From stapes it foes to the cochlea. Cochlea is fluid filled and contains hearing receptors.

• Cochlea has the organ of Corti which transmit the vibrations to the cochlear duct and finally to the cochlear nerve.

The plants which produce two types of spores with different sizes, large →macro) and small →micro), are called heterosporous. It is found in genera like Salvina and Selaginella. The megaspores produce megagametophytes →female gametophytes) and microspores produce microgametophytes →male gametophytes). The female gametophytes in these plants are retained on the parent sporophytes for variable periods. The development of the zygotes into young embryos takes place within the female gametophytes. The presence of heterospory in pteridophytes indicates the evolution of gymnosperms from pteridophytes.

Karyokinesis →nuclear division) is divided into 4 stages –

Prophase, Metaphase, Anaphase and Telophase

a. Appearance of nucleolus – telophase

b. Division of centromere – Anaphase

c. Replication of DNA – Interphase

Sulphur is one of the macronutrients required by the plants. Plants obtain sulphur in the form of sulphate →). Sulphur is the main constituent of several coenzymes, vitamins →thiamine, biotin, Coenzyme A) and ferredoxin which are present in some biochemical pathway.

It is present in two amino acids – cysteine and methionine.

In most of the higher plants, the growing apical bud inhibits the growth of the lateral →axillary) buds, a phenomenon called apical dominance. This is because of the hormone auxin synthesised in the apical bud that inhibits lateral bud development.

Removal of shoot tips →decapitation) usually results in the growth of lateral buds.

While eating peach or pear it is usually seen that some stone like structures get entangled in the teeth are sclereids →stone cells).

The sclereids are spherical, oval or cylindrical, highly thickened dead cells with very narrow cavities →lumen).

These are commonly found in the fruit walls of nuts; pulp of fruits like guava, pear and sapota; seed coats of legumes and leaves of tea.

Succulents are known to keep their stomata closed during the day to check transpiration. So in order to meet their photosynthetic CO₂ requirements, they fix CO₂ into organic compound using PEP carboxylase at night, when the stomata are open.

PEP + CO₂ --→ OAA

OAA --→ --→--→Malic Acid

The activities of the gastro-intestinal tract are under neural and hormonal control for proper coordination of different parts. The sight, smell and/or the presence of food in the oral cavity can stimulate the secretion of saliva. Gastric and intestinal secretions are also, similarly, stimulated by neural signals. The muscular activities of different parts of the alimentary canal can also be moderated by neural mechanisms, both local and through CNS. Hormonal control of the secretion of digestive juices is carried out by local hormones produced by the gastric and intestinal mucosa.

The arrangement of ovules within the ovary is known as placentation. The part of the ovary where the funiculus →equivalent to an umbical cord) attaches is referred to as the placenta.

There are 5 types of placentation –

• Marginal

• Axile

• Parietal

• Free-central

• Basal

Root nodules of pulse plant are the sites of nitrogen fixation. The nitrogen fixation is done by the enzyme nitrogenate →an Mo-Fe protein). Other requirements for this process are electrons, protons and ATP molecules. Nitrogen is bound to the surface of the enzyme and it is reduced to ammonia in a stepwise reaction with the help of reducing agents and hydrolysis of ATP. When eight electrons →and 8H⁺) are accepted by N₂, 2 NH₃ are released from the enzyme. The biochemical pathway can be summarized by the reaction below:

N₂ + 8 e^- + 8 H⁺+ 16 ATP 2 NH₃ + 12 ADP + 12 Pi

The end product of nitrogen fixation is ammonia.

The ammonia is protonated at physiological pH to form NH₄⁺ ion which is further used to synthesize amino acids in plants. The formation of amino acids takes place in two ways – transamination and reductive amination.

OR

Since each element has one or more specific structural or functional role in plants, in the absence of any particular element, plants show certain morphological changes. These morphological changes are indicative of certain element deficiencies and are called deficiency symptoms.

a. It is actively mobilized

b. Highly mobile – Nitrogen, Magnesium

Relatively immobile – Sulphur, Calcium

c. For elements that are actively mobilised within the plants and exported to young developing tissues, the deficiency symptoms tend to appear first in the older tissues.

The deficiency symptoms tend to appear first in the young tissues whenever the elements are relatively immobile and are not transported out of the mature organs.

This idea can be used in horticulture and agriculture to get a broad idea of deficiency elements in plants.

i. Muscle contraction is initiated by a signal sent by the central nervous system →CNS) via a motor neuron.

ii. A motor neuron along with the muscle fibres connected to it constitute a motor unit.

iii. The junction between a motor neuron and the sarcolemma of the muscle fibre is called the neuromuscular junction or motor-end plate.

iv. A neural signal reaching this junction releases a neurotransmitter →Acetyl choline) which generates an action potential in the sarcolemma. This spreads through the muscle fibre and causes the release of calcium ions into the sarcoplasm.

v. Increase in Ca²⁺ level leads to the binding of calcium with a subunit of troponin on actin filaments and thereby remove the masking of active sites for myosin.

vi. Utilising the energy from ATP hydrolysis, the myosin head now binds to the exposed active sites on actin to form a cross bridge.

vii. This pulls the attached actin filaments towards the centre of ‘A’ band. The ‘Z’ line attached to these actions are also pulled inwards thereby causing a shortening of the sarcomere, i.e., contraction.

viii. A new ATP binds and the cross-bridge is broken. The ATP is again hydrolysed by the myosin head and the cycle of cross bridge formation and breakage is repeated causing further sliding.

ix. The process continues till the Ca²⁺ ions are pumped back to the sarcoplasmic cisternae resulting in the masking of actin filaments.

i. This causes the return of ‘Z’ lines back to their original position, i.e., relaxation.

OR

When the calf fondles it causes a suckling stimulus due to which a neuroendocrine reflex is created. This leads to the release of oxytocin from the neurohypophysis. Oxytocin causes contraction of smooth muscle of the udder resulting in milk flow. An intra-udder injection of hormone like oxytocin would do the same.