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All questions of November Week 3 for NEET Exam

5 g of ice at 0° C is mixed with 10 g of water at 10° C. The temperature of the mixture is:
  • a)
    2°C
  • b)
    0°C​
  • c)
    5°C
  • d)
    2.5°C
Correct answer is option 'B'. Can you explain this answer?

Riya Banerjee answered
Heat absorbed by 5g ice when it converted to at 0° C = 5 x 80 = 400 cal.
Heat liberated by 10g water at 10° C to 0° C = 100 cal
Hence there is 15g water at 0° C and 300 cal needs to be liberated , thus for some amount of water converts into ice, hence the temp of mixture is 0° C.
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Can you explain the answer of this question below:

Water is used as coolant in automobiles radiators because

  • A:

    it has high specific heat capacity

  • B:

    it is easily available

  • C:

    it is easy to carry

  • D:

    it is cheap

The answer is a.

Lavanya Menon answered
Water is used as a coolant in automobiles radiators because it has high specific heat capacity. So, it absorbs a large amount of heat for a degree rise in temperature.

A piece of iron of mass 100g is kept inside a furnace for a long time and Jthen put in a calorimeter of water equivalent 10g containing 240g of water at 20°C. The mixture attains an equilibrium temperature of 60°C. Find the temperature of the furnace. Specific heat capacity of iron = 470J/kg-°C.
  • a)
    500°C
  • b)
    900°C
  • c)
    953.6∘C
  • d)
    706.80 °C
Correct answer is option 'C'. Can you explain this answer?

Gaurav Kumar answered
Mass of Iron = 100g
Water Eq of caloriemeter = 10g
Mass of water = 240g
Let the Temp. of surface = 0ºC
Siron = 470J/kg°C 
Total heat gained = Total heat lost.
So,100/1000× 470 × (θ – 60) = 250/1000 × 4200 × (60 – 20)
⇒ 47θ – 47 × 60 = 25 × 42 × 40
⇒  θ = 4200 + 2820/47= 44820/47 =953.61°C

According to law of calorimetry, which of the given relation is true?
  • a)
    Heat gained ≥ Heat lost
  • b)
    Heat gained = Heat lost
  • c)
    Heat gained > Heat lost
  • d)
    Heat lost > Heat gained
Correct answer is option 'B'. Can you explain this answer?

Anjali Iyer answered
A principle of calorimetry states that if there is no loss of heat in surrounding the total heat lost by hot body equal to the total heat gained by a cold body.

i.e. heat loss = heat gain

A device in which heat measurement can be made is called
  • a)
    Joule meter
  • b)
    Calorimeter
  • c)
    Thermal meter
  • d)
    Gauge meter
Correct answer is option 'B'. Can you explain this answer?

Shanaya Tiwari answered
Calorimeter:
The correct device for heat measurement is a calorimeter. Calorimeters are used to measure the heat involved in a chemical reaction or physical change. They work based on the principle of conservation of energy, where the heat released or absorbed during a reaction is measured by the change in temperature of a known mass of water.

How does a Calorimeter work?
- A known quantity of the substance undergoing the reaction is placed in the calorimeter along with a known quantity of water.
- The initial temperature of the water and the substance is recorded.
- The reaction takes place, and the heat released or absorbed causes a change in temperature of the water.
- By measuring the change in temperature, the heat exchanged can be calculated using the specific heat capacity of water.
- Calorimeters are designed to minimize heat loss to the surroundings to ensure accurate measurements.

Types of Calorimeters:
- There are different types of calorimeters such as bomb calorimeters, coffee cup calorimeters, and differential scanning calorimeters, each suitable for different applications.
- Bomb calorimeters are commonly used for measuring the heat of combustion of substances.
- Coffee cup calorimeters are simpler and are often used in educational settings to demonstrate heat exchange principles.
In conclusion, a calorimeter is the appropriate device for heat measurement as it allows for accurate determination of the heat involved in a reaction or process.

Auxin was isolated from tips of coloeptile of oat seedlings by
  • a)
    Miller
  • b)
    F.W.Went
  • c)
    E.Kurosawa
  • d)
    Skoog
Correct answer is option 'B'. Can you explain this answer?

Naina Bansal answered
F. W Went first isolated the Auxins  in 1928 from the tips of the coleooptiles of oat seedlings. F.W Went was secondly able to isolate a chemical from coleoptile juice.

Type of cambium located between phloem and xylem is classified as
  • a)
    shoot cambium
  • b)
    root cambium
  • c)
    vascular cambium
  • d)
    cork cambium
Correct answer is option 'C'. Can you explain this answer?

Ankit Patel answered
The vascular cambium is a type of cambium located between the phloem and xylem in plants. It is responsible for secondary growth in plants, which results in an increase in girth of the stem or root.

Structure of vascular cambium:
The vascular cambium consists of a single layer of meristematic cells that divide to form secondary xylem cells towards the inside and secondary phloem cells towards the outside.

Function of vascular cambium:
The vascular cambium is responsible for the production of new xylem and phloem cells, which allows for the growth of the plant. It also helps in the transportation of water and nutrients from the roots to the rest of the plant.

Importance of vascular cambium:
The vascular cambium plays a crucial role in the life of a plant as it is responsible for the growth and development of the stem and root. Without the vascular cambium, plants would not be able to grow taller or wider, and they would eventually die.

Conclusion:
The vascular cambium is a vital part of the plant's anatomy as it is responsible for the growth and development of the stem and root. Its role in the production of new xylem and phloem cells is essential for the transportation of water and nutrients throughout the plant.

Auxins are generally produced in
  • a)
    Phloem
  • b)
    root and shoot tips
  • c)
    xylem
  • d)
    leaves
Correct answer is option 'B'. Can you explain this answer?

Pallavi Choudhary answered
Explanation:
Auxins are a group of plant hormones that play a crucial role in various plant growth and developmental processes. They are primarily produced in the shoot and root tips of plants.

- Shoot tips: In the shoot tips, auxins are mainly produced in the apical meristem region, which is responsible for the growth and development of the stem and leaves. The apical meristem contains undifferentiated cells that can give rise to different types of tissues. Auxins produced in this region help in the elongation of the stem and the formation of new leaves.

- Root tips: In the root tips, auxins are mainly produced in the root apical meristem, which is responsible for the growth and development of the root system. The root apical meristem contains undifferentiated cells that can give rise to different types of root tissues. Auxins produced in this region help in the elongation of the root and the formation of lateral roots.

Other sources of auxins:

- Leaves: Although auxins are primarily produced in the shoot and root tips, leaves also contain a small amount of auxins. These auxins play a role in leaf abscission, which is the shedding of leaves from the plant.

- Phloem: The phloem is a vascular tissue that transports nutrients and other molecules from the leaves to other parts of the plant. Auxins are also transported through the phloem to other parts of the plant.

- Xylem: The xylem is a vascular tissue that transports water and minerals from the roots to other parts of the plant. Although auxins are primarily produced in the shoot and root tips, they can also be transported through the xylem to other parts of the plant.

Conclusion:
In conclusion, auxins are primarily produced in the shoot and root tips of plants, where they play a crucial role in various growth and developmental processes. Although auxins can also be found in other parts of the plant, their main source is the shoot and root tips.

If GA3 is applied to the rice seedlings, the plant will show
  • a)
    Delayed ripening
  • b)
    Early flowering
  • c)
    Dwarfing
  • d)
    Extra elongation
Correct answer is option 'D'. Can you explain this answer?

Raza Great answered
If GA3 is applied to rice seedlings: The rice seedlings will show extra elongation and increase in height. They may also remain sterile.

It is the testing of a biological activity like growth response of a substance by employing a living material like plant or plant part.
  • a)
    Separation
  • b)
    Fractionalisation
  • c)
    Bioassay
  • d)
    Autopsy
Correct answer is option 'C'. Can you explain this answer?

Swara Desai answered
Testing of biological activity like growth response of a substance by employing a living material like plant or plant part is called bioassay. It is used to know the effect of substance on plant growth.

Select the set of compounds with oxidation-reduction duality.
  • a)
    Cl2, H3PO4, HCHO, HNO2
  • b)
    Cl2, H3PO3, C6H5CHO, H2O2
  • c)
    Br2, H3PO2, CH3CHO, H3PO4
  • d)
    CrO2Cl2, KMnO4, SO3, CO2
Correct answer is option 'B'. Can you explain this answer?

Neha Sharma answered
Com pounds having oxidising and reducing nature in given reaction are said to have oxidation-reduction duality. Such compounds are said to undergo disproportionation reaction.



(This is called Cannizzaro reaction.)

Note Such compounds have O.N. of the affected atoms intermediate of oxidation part and reduction part

Mathematically arithmetic growth is expressed as
  • a)
    Lt = L0.rt
  • b)
    Lt = L0/rt
  • c)
    Lt = L0 + rt
  • d)
    Lt = L0 - rt
Correct answer is option 'C'. Can you explain this answer?

Anshika Shah answered
Arithmetic growth is a type of growth where a quantity increases or decreases by a fixed amount over a fixed interval of time. It can be represented mathematically using the formula Lt = L0 + rt, where Lt is the value of the quantity at time t, L0 is the initial value of the quantity, r is the rate of change, and t is the time interval.

Explanation of the formula:
- Lt represents the value of the quantity at time t. This is the value that we want to find.
- L0 represents the initial value of the quantity. This is the starting point of the growth.
- r represents the rate of change. It determines how much the quantity changes over the time interval.
- t represents the time interval. It is the amount of time that has passed since the initial value.

In arithmetic growth, the rate of change is constant. This means that the quantity increases or decreases by the same amount for each unit of time. The formula Lt = L0 + rt captures this concept by adding the rate of change multiplied by the time interval to the initial value.

For example, let's say we have an initial quantity of 100 and a rate of change of 5. If we want to find the value of the quantity after 3 time intervals, we can use the formula Lt = 100 + 5 * 3 = 115. This means that the quantity has increased to 115 after 3 time intervals.

In option C, Lt = L0 + rt, the formula correctly represents arithmetic growth. The other options do not accurately capture the concept of arithmetic growth or contain incorrect mathematical operations.

Reduction is defined in terms of
I. electronation and hydrogenation
II. deelectronation and gain of oxygen
III. increase in oxidation number
IV. decrease in oxidation number
Select the correct terms
  • a)
    I and IV
  • b)
    I and III
  • c)
    II and II
  • d)
    I and II
Correct answer is option 'A'. Can you explain this answer?

Siddharth Mehra answered
Reduction is defined in terms of electronation and hydrogenation

Reduction is a chemical process that involves the gain of electrons or a decrease in oxidation number. It can be defined in terms of two main reactions: electronation and hydrogenation.

I. Electronation:
- Electronation refers to the process of gaining electrons. In a reduction reaction, a molecule, ion, or atom accepts one or more electrons, resulting in a more negative charge.
- For example, in the reaction: X + e- -> X-, the atom X gains an electron, and its oxidation number decreases. This is a reduction reaction.

II. Hydrogenation:
- Hydrogenation is a specific type of reduction reaction where hydrogen atoms are added to a molecule.
- During hydrogenation, the molecule gains hydrogen atoms, and its oxidation number decreases. This is a reduction reaction.
- For example, in the reaction: X + H2 -> XH2, the molecule X gains hydrogen atoms, and its oxidation number decreases. This is a reduction reaction.

III. Increase in oxidation number:
- Increase in oxidation number is not associated with reduction but with oxidation.
- In oxidation, the oxidation number of an atom, ion, or molecule increases, indicating the loss of electrons.
- Reduction, on the other hand, involves the gain of electrons, resulting in a decrease in oxidation number.

IV. Decrease in oxidation number:
- Decrease in oxidation number is directly associated with reduction.
- Reduction reactions involve the gain of electrons, leading to a decrease in oxidation number.
- For example, if the oxidation number of an atom changes from +2 to 0, it has undergone reduction because its oxidation number has decreased.

Conclusion:
Based on the definitions of reduction and the given options, the correct terms that define reduction are I. electronation and IV. decrease in oxidation number. These two terms accurately describe the process of reduction, where electrons are gained and the oxidation number decreases. Therefore, option A. (I and IV) is the correct answer.

Which of the following meristem is not responsible for the secondary growth of plants?
  • a)
    Apical meristem
  • b)
    Vascular cambium
  • c)
    Lateral meristem
  • d)
    Cork cambium
Correct answer is option 'A'. Can you explain this answer?

Samarth Nambiar answered
Understanding Plant Meristems
In plant biology, meristems are regions where active cell division occurs, leading to growth. They can be classified into two main types: primary and secondary meristems.
Primary Growth vs. Secondary Growth
- Primary Growth: This occurs at the tips of roots and shoots, facilitated by the apical meristem. It results in the elongation of the plant, allowing it to grow taller or deeper.
- Secondary Growth: This is responsible for the thickening of stems and roots, which occurs later in a plant's life. Secondary growth is primarily facilitated by lateral meristems.
Meristems Involved in Secondary Growth
- Vascular Cambium: This lateral meristem produces new vascular tissues (xylem and phloem), contributing significantly to the thickness of the plant.
- Cork Cambium: Another lateral meristem, cork cambium gives rise to the periderm, which replaces the epidermis in older stems and roots, adding protective layers.
Why Apical Meristem is Not Involved in Secondary Growth
- The apical meristem is exclusively responsible for primary growth. It is located at the tips of roots and shoots and does not contribute to the thickening of the plant body.
- Since secondary growth involves the increase in girth rather than height, apical meristem does not play a role in this process.
Conclusion
Thus, the correct answer to the question is option 'A', as the apical meristem is not responsible for secondary growth, while the vascular cambium and cork cambium are crucial for this process.

All the cells of the plant are descendants of which of the following?
  • a)
    Apical tissue
  • b)
    Intercalary tissue
  • c)
    Meristem
  • d)
    Zygote
Correct answer is option 'D'. Can you explain this answer?

Arpita Saha answered
Understanding Plant Cell Origins
The correct answer to the question regarding the descendants of all plant cells is the zygote. Here’s a detailed explanation:
What is a Zygote?
- A zygote is the initial cell formed when two gametes (sperm and egg) fuse during fertilization.
- This single-celled entity contains genetic material from both parents, representing the beginning of a new organism.
Development from Zygote to Plant Cells
- The zygote undergoes a series of mitotic divisions, leading to the formation of an embryo.
- As the embryo develops, it differentiates into various types of tissues and cells, eventually forming all the organs of the plant.
Comparison with Other Options
- Apical Tissue: This refers to the regions of active growth at the tips of roots and shoots but arises from the meristematic cells developed from the zygote.
- Intercalary Tissue: These tissues are found between mature tissues in plants, especially in monocots, and are also derived from the meristem.
- Meristem: Meristematic tissues are regions of undifferentiated cells and are responsible for growth; however, they originate from the zygote as well.
Conclusion
- All plant cells trace their lineage back to the zygote, making it the foundational cell from which every plant cell type ultimately derives.
- This highlights the importance of the zygote in the plant life cycle and cellular development.

In dicotyledonous plants, girth of stem and root increase due to
  • a)
    Development
  • b)
    Primary growth
  • c)
    Secondary growth
  • d)
    Differentiation
Correct answer is option 'C'. Can you explain this answer?

Maitri Mukherjee answered
In dicotyledonous plants, girth of stem and root increase due to secondary growth. Secondary growth occurs due to cambium formation in stem and root.

The correct sequence leading to the growth curve
  • a)
    lag,stationary,log phases
  • b)
    log,lag , stationary phases
  • c)
    lag, log, stationary phases
  • d)
    stationary,log,lag phases
Correct answer is option 'C'. Can you explain this answer?

Bhavya Yadav answered
The initial growth is slow (lag phase), and it increases rapidly thereafter – at an exponential rate (log or exponential phase). Here, both the progeny cells following mitotic cell division retain the ability to divide and continue to do so. However, with limited nutrient supply, the growth slows down leading to a stationary phase.


Coefficient x, y and z are respectively 
  • a)
    a
  • b)
    b
  • c)
    c
  • d)
    d
Correct answer is option 'C'. Can you explain this answer?

Hansa Sharma answered

Cross -multiply by change in oxidation number and balance H by H+ ions.

Thus, x = 2, y = 5 and z = 6 

Abscissic acid is also known as
  • a)
    Ripening hormone
  • b)
    Stress hormone
  • c)
    Shoot hormone
  • d)
    Cell hormone
Correct answer is option 'B'. Can you explain this answer?

Swara Desai answered
ABA stimulates the closure of stomata in the epidermis and increases the tolerance of plants to various kinds of stresses.Therefore, it is also called the stress hormone.

Higher plants possess specific areas which take part in the formation of new cells. These area are called
  • a)
    Meristems
  • b)
    Parenchyma
  • c)
    Permanent tissue
  • d)
    Collenchyma
Correct answer is option 'A'. Can you explain this answer?

Bhavya Yadav answered
The tissues that have ability of cell division located in specific area are called meristem. They are located at stem and root tips, nodes of stem and intercalary region.

Development is the sum of how many processes?
  • a)
    One
  • b)
    Three
  • c)
    Two
  • d)
    Four
Correct answer is option 'C'. Can you explain this answer?

EduRev NEET answered
  • Development is the sum of two processes-growth and differentiation.
  • To begin with, it is essential and sufficient to know that the development of a mature plant from a zygote follows a precise and highly ordered succession of events.

The undifferentiated mass of parenchymatous cells are called
  • a)
    Cambium
  • b)
    Callus
  • c)
    Carotenoids
  • d)
    Cytokinesis
Correct answer is option 'B'. Can you explain this answer?

Swara Desai answered
The callus (a mass of undifferentiated cells) proliferated only if, in addition to auxins the nutrients medium was supplemented.

H2O can be oxidised to
  • a)
     H2 and O2
  • b)
    O2-
  • c)
    OH-
  • d)
    O2
Correct answer is option 'D'. Can you explain this answer?

Nandini Iyer answered
The oxidation state of O atom is not always - 2 but it can be - 2 to +2. Similarly oxidation state of H atom is from - 1 to +1(+1 in a compound and - 1 in metal hydride but it can also be 0 as the range is - 1,0,+1) .
The oxidation state, sometimes referred to as oxidation number, is an indicator of the degree of oxidation (loss of electrons) of an atom in a chemical compound.
H2O is a compound. Hence, H -> +1 and O -> - 2 as H atom can lose 1 electron that's why oxidation state of H atom is +1
correct answer is option D

Select the correct statement(s).
  • a)
    Compound of lower oxidation state is formed, if the reducing agent is in excess
  • b)
    Compound of higher oxidation state is formed, if the oxidising agent is in excess
  • c)
    Compound of higher oxidation state is formed, if the reducing agent is in excess
  • d)
    Compound of lower oxidation state is formed, if the oxidising agent is in excess
Correct answer is option 'A,B'. Can you explain this answer?

Manisha Patel answered

Carbon is reducing agent (R) and oxygen is oxidising agent (O). CO with oxidation number of C (= + 2) is formed.
(R) is inexcess hence, product of lower (oxidation number) is formed.
Thus, (a) is correct.

(O) is in excess hence product of higher oxidation number is formed. Thus, (b) is also correct.

In rosette plants, bolting is due to
  • a)
    Gibberellins
  • b)
    Cytokinins
  • c)
    ABA
  • d)
    Auxins
Correct answer is option 'A'. Can you explain this answer?

Vandana Sharma answered
Understanding Bolting in Rosette Plants
Bolting is a critical process in the life cycle of rosette plants, which are characterized by a rosette of leaves close to the ground. This process is primarily triggered by certain environmental factors and hormonal changes.
Role of Gibberellins
- Definition: Gibberellins are a class of plant hormones that play a significant role in regulating growth and development.
- Initiation of Bolting: In rosette plants, gibberellins promote the transition from vegetative growth to flowering. They stimulate the elongation of stems and the development of flowers, which is essential for reproduction.
- Environmental Triggers: Factors such as increased daylight length (photoperiod) and temperature changes often induce the synthesis of gibberellins, leading to bolting.
Comparison with Other Hormones
- Cytokinins: While cytokinins promote cell division and shoot development, they do not directly trigger bolting in rosette plants.
- ABA (Abscisic Acid): ABA generally acts as a growth inhibitor and is associated with stress responses, thus not playing a role in promoting bolting.
- Auxins: These hormones are involved in various growth processes, including stem elongation and root development, but are not the primary drivers of bolting.
Conclusion
In summary, gibberellins are the key hormones responsible for triggering the bolting process in rosette plants. They facilitate the transition from a vegetative state to flowering by promoting stem elongation, making them essential for the reproductive phase in these plants. Understanding the role of gibberellins can provide insights into the developmental biology of various plant species.

Identify intramolecular oxidation-reduction reaction.
  • a)
  • b)
  • c)
  • d)
Correct answer is option 'A,B,C,D'. Can you explain this answer?

Rashi Sharma answered




In all of the above reactions, oxidised and reduced part are in same species, hence, intramolecular redox reactions.

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