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All questions of June Week 2 for NEET Exam

The cross-section of the body of an invertebrate is given below. Identify the animal which has this body plan.
  • a)
    Cockroach
  • b)
    Earthworm
  • c)
    Roundworm
  • d)
    Planaria
Correct answer is option 'D'. Can you explain this answer?

Stepway Academy answered
  • It has three-layered body wall which includes ectoderm, endoderm, and mesoderm. 
  • Acoelomates lack a body cavity, and instead the space between the body wall and the digestive tract is filled with muscle fibres and loose tissue called parenchyma.
  • It acts as a skeletal support, nutrient storage, motility, reserves of regenerative cells and transporting materials.
  • Planaria belongs to phylum Platyhelminthes.
  • These are flatworms and has acoelomate body plan.
Hence, the correct option is D.
NCERT Reference: Topic Phylum – Platyhelminthes” of chapter Animal Kingdom
 
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Which phylum is a coelom and triploblastic animals?
  • a)
    Phylum Ctenophora
  • b)
    Phylum Annelida
  • c)
    Phylum Coelenterata
  • d)
    Phylum Porifera
Correct answer is option 'B'. Can you explain this answer?

Raghav Bansal answered
Annelida are aquatic (marine and freshwater) or terrestrial, free-living, and sometimes parasitic. They are bilateral symmetric and triploblastic.

A reptile having four chambered heart is
a)Snake
b)Salamander
c)Crocodile
d)Lizards
Correct answer is option 'C'. Can you explain this answer?

Prakhar Maheshwari answered
Except for crocodilians, which have a four-chambered heart, all reptiles have a three-chambered heart consisting of two atria and one ventricle.

What is the main excretory organ in insects?
  • a)
    Proboscis gland
  • b)
    Malphighian tubules
  • c)
    Gills
  • d)
    Excretory pore
Correct answer is option 'B'. Can you explain this answer?

Rajat Kapoor answered
Malpighian tubule
The Malpighian tubule system is a type of excretory and osmoregulatory system found in some insects, myriapods, arachnids, and tardigrades. The system consists of branching tubules extending from the alimentary canal that absorbs solutes, water, and wastes from the surrounding hemolymph.

Species going to extinct due to low reproductive rate is
  • a)
    Island sps
  • b)
    Bald eagle
  • c)
    Lion
  • d)
    Giant panda
Correct answer is option 'D'. Can you explain this answer?

Rajesh Datta answered
Giant panda is going to extinct due to low reproductively rate. They live in mountain ranges in central china. There reproductively rate is varyless due to climatic conditions.

Two masses are in the ratio 1:5. What is ratio of their inertia?
  • a)
    1:5
  • b)
    5:1
  • c)
    1:25
  • d)
    25:1
Correct answer is option 'A'. Can you explain this answer?

Sagar Goyal answered
 
Force of inertia = ma
Let the masses be 1x and 5x
Force of inertia for 1st body= 1x * a
Force of inertia for 2nd = 5x * a
Ratio= x * a / 5x * a = 1:5

Which law is in control of a spacecraft that cruises through space at a constant speed without using any fuel?
  • a)
    Universal law of gravitation
  • b)
    Newton’s third law
  • c)
    Newton’s second law
  • d)
    Newton’s first law
Correct answer is 'D'. Can you explain this answer?

Rajveer Kumar answered
Given information:
- Mass of the object = 6 kg
- Three forces acting on the object:
- F1 = 20i + 30j N
- F2 = 8i - 50j N
- F3 = 2i + 2j N

To find: Acceleration of the object

Solution:
- We know that the net force acting on the object, F_net = F1 + F2 + F3
- Using vector addition, we can find the net force: F_net = (20+8+2)i + (30-50+2)j = 30i - 18j N
- Now, using Newton's second law of motion, F_net = m*a, where m is the mass of the object and a is the acceleration produced.
- Substituting the values, we get: 30i - 18j = 6*a
- Dividing both sides by 6, we get: a = (30/6)i - (18/6)j = 5i - 3j m/s^2

Therefore, the acceleration of the object is 5i - 3j m/s^2, which is option 'B'.

The excretory organ of Saccoglossus is
  • a)
    Malphighian tubules
  • b)
    Proboscis gland
  • c)
    Gills
  • d)
    Excretory pore
Correct answer is option 'B'. Can you explain this answer?

Pooja Mehta answered
A proboscis is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular mouth parts used for feeding and sucking. In vertebrates, a proboscis is an elongated nose or snout.

How many chambers are there in camel’s stomach?Identify the animal given below. Mention its phylum.
  • a)
    1 chamber, Ascidia and phylum Chordata
  • b)
    3 Chamber, Spongilla and phylum Porifera
  • c)
    3 chambers, Euspongia and phylum Porifera
  • d)
    4 chamber, Aurelia and phylum Coelenterata
Correct answer is option 'C'. Can you explain this answer?

Shiksha Academy answered
Euspongia, which belongs to the phylum Porifera, is commonly known as a sponge. Sponges are some of the simplest and most primitive animals in the animal kingdom.
Hence, the correct option is C.
NCERT Reference: Topic: Phylum – Porifera” of chapter Animal Kingdom

Which group of chordates possesses sucking and circular mouth without jaws?
  • a)
    ClassChondrichthyes
  • b)
    Class Cyclostomata
  • c)
    Class Osteichthyes
  • d)
    Both (b) and (c) 
Correct answer is option 'B'. Can you explain this answer?

Pooja Mehta answered
 Class-Cyclostomata is comprised of, the living jawless fishes. Their mouth is circular and lack jaws, hence they are also called agnathans.  It is surrounded by tentacles (e.g., lampreys and hellish). These also presses retractable teeth.       

Animals which possess cleidoic egg exhibit
  • a)
    External fertilisation and external development
  • b)
    External fertilisation and internal development
  • c)
    Internal fertilisation and internal development
  • d)
    Internal fertilisation and external development
Correct answer is option 'D'. Can you explain this answer?

Rajeev Saxena answered
Cleidoic eggs are laid by reptiles & birds. These eggs have protective shell which is porous to air and may be flexible or calcareous (hard). Birds and reptiles exhibit internal fertilization and laid eggs contain all the food the embryo needs for external development. 

Silk produced by Antheraea Mylitta is called
  • a)
    Eri silk
  • b)
    Muga silk
  • c)
    Mysore silk
  • d)
    Tasar silk
Correct answer is option 'D'. Can you explain this answer?

Rajat Kapoor answered
Tropical Tasar: Tasar (Tussah) is copperish colour, coarse silk mainly used for furnishings and interiors. It is less lustrous than mulberry silk, but has its own feel and appeal. Tasar silk is generated by the silkworm, Antheraea mylitta which mainly thrive on the food plants Asan and Arjun.

Air bladder is absent in
  • a)
    Sea horse
  • b)
    Shark
  • c)
    Flying fish
  • d)
    All of the above
Correct answer is option 'B'. Can you explain this answer?

Roshni Tiwari answered
Explanation:
Air bladder is a gas-filled sac that helps fish to maintain buoyancy in water. However, not all fish have air bladders. The correct answer to the given question is option B, i.e., shark, as sharks do not have air bladders.

Reasons why sharks do not have an air bladder are:

1. Buoyancy control: Sharks have a special organ called the liver that is filled with oil. This oil is less dense than water and provides buoyancy to the shark, allowing it to stay afloat.

2. Depth control: Unlike bony fish that have a swim bladder to adjust their depth in water, sharks are able to control their depth by swimming. They can swim at different angles to adjust their depth in water.

3. Adaptation to environment: Sharks have evolved to live in their environment, and their body shape and buoyancy control mechanisms have adapted to suit their needs.

Therefore, it can be concluded that while some fish have air bladders to maintain buoyancy in water, sharks have evolved different mechanisms to control their buoyancy and depth in water.

The phylum in which adults exhibit radial symmetry and larva exhibit bilateral symmetry is
  • a)
    Phylum Arthropoda
  • b)
    Phylum Echinodermata
  • c)
    Phylum Annelida
  • d)
    Phylum Aschelminthes
Correct answer is option 'B'. Can you explain this answer?

Jyoti Kapoor answered
 Symmetry is an attribute of an organism showing regularity in body parts on a plane or around an axis. In Phylum Echinodermata, the adult echinoderms are radially symmetrical but the larvae are bilaterally symmetrical. 

Which of the following will have the most negative electron gain enthalpy and which one the least negative? P, S, Cl, F.
  • a)
    Cl, P
  • b)
    P,Cl
  • c)
    P,S
  • d)
    none
Correct answer is option 'A'. Can you explain this answer?

Sinjini Pillai answered
**Answer:**

The electron gain enthalpy is the energy released when an atom gains an electron to form a negative ion. It is a measure of the tendency of an atom to accept an electron.

To determine which element will have the most negative electron gain enthalpy and which one will have the least negative, we need to consider the factors that influence electron gain enthalpy.

1. **Nuclear charge**: The greater the nuclear charge, the stronger the attraction for the incoming electron, resulting in a more negative electron gain enthalpy.
2. **Atomic size**: The smaller the atomic size, the closer the valence electrons are to the nucleus, resulting in a stronger attraction for the incoming electron and a more negative electron gain enthalpy.

Considering these factors, we can analyze the elements given in the options:

a) Cl, P: Chlorine (Cl) has a higher nuclear charge than Phosphorus (P), so it will have a greater attraction for the incoming electron. Additionally, chlorine is smaller in size compared to phosphorus. Therefore, chlorine will have the most negative electron gain enthalpy, and phosphorus will have a less negative electron gain enthalpy.

b) P, Cl: As mentioned above, chlorine (Cl) has a higher nuclear charge and is smaller in size compared to phosphorus (P). Therefore, chlorine will have a more negative electron gain enthalpy, and phosphorus will have a less negative electron gain enthalpy.

c) P, S: Sulfur (S) has a higher nuclear charge and is smaller in size compared to phosphorus (P). Therefore, sulfur will have a more negative electron gain enthalpy, and phosphorus will have a less negative electron gain enthalpy.

d) None: The answer cannot be "none" since we have already determined that chlorine will have the most negative electron gain enthalpy.

In conclusion, the correct answer is option 'A': Cl will have the most negative electron gain enthalpy, and P will have the least negative electron gain enthalpy.

Which of the following statements is false?
  • a)
    Alkali metals form covalent bonds with oxygen.
  • b)
    Alkali metals have relatively low first ionization energies
  • c)
    Alkali metals forms oxides that act as basic anhydrides.
  • d)
    Alkali metals usually have a +1 oxidation state
Correct answer is option 'A'. Can you explain this answer?

Pooja Mehta answered
Lithium, sodium and potassium all react vigorously with water. Hydrogen gas bubbles off and, in the case of potassium, this burns with a lilac flame. The metal hydroxide is formed which is a strong alkali. Alkali metals need to be stored under oil to prevent them reacting with the oxygen and water vapour in the air.

Read the following statements:

i) Spider and mosquito possess compound eye
ii) Jelly fishes possess cnidoblasts but comb-jellies lack them.
iii) All animals having true coelom are characterized by the presence of bilateral symmetry usually, tube-within-tube body plan, presence of mesoderm and true segmentation
iv) The animals of the phylum Porifera have originated from colonial protozoans.

Which of the above statements are correct?
  • a)
    i, ii, iv
  • b)
    iii, iv
  • c)
    i, iii
  • d)
    ii, iii
Correct answer is option 'A'. Can you explain this answer?

Stepway Academy answered
i) Spider and mosquito possess compound eyes. The eyes of most insects, which are composed of many light-sensitive elements, each having its own reflective system and each forming a portion of an image.
ii) Jelly fishes possess cnidoblasts but comb-jellies lack them. Cnidoblasts are features of Coelenterata (Cnidaria) and comb-jellies come under the phylum Ctenophora.
iii) All animals with a true coelom usually exhibit bilateral symmetry, a tube-within-tube body plan, presence of mesoderm, and true segmentation.
iv) The animals of the phylum Porifera have indeed originated from colonial protozoans.
Thus, the correct statements are i, ii, and iv. The answer is Option A.

The sequence of ionic mobility in aqueous solution is 
  • a)
    K+ > Na+ > Rb+ > Cs+
  • b)
    Cs+ > Rb+ > K+ >Na+
  • c)
    Rb+ > K+> Cs+ > Na+
  • d)
    Na+ > K+ >Rb+ >Cs+
Correct answer is option 'B'. Can you explain this answer?

Hansa Sharma answered
Smaller the size of cation, higher will be the hydration and its effective size will increase and hence mobility in aqueous solution will decrease. Larger size ions have more ionic mobility due to less hydration. Thus the degree of hydration of M+ ions decreases from Li+ to Cs+. Consequently the radii of the hydrated ion decreases from Li+ to Cs+. Hence the ionic conductance of these hydrated ions increases from Li+ to Cs+ 

Dust can be removed out of a blanket using
  • a)
    Law of inertia
  • b)
    Newton’s second law of motion
  • c)
    Newton’s third law of motion
  • d)
    Newton’s law of gravitation
Correct answer is 'A'. Can you explain this answer?

Pooja Shah answered
When a blanket is bitten with a stick or something then particles of blanket come into motion while dust particles remains in rest thus comes out which shows law of inertia.

Match each item in Column I with one item in Column II and choose your answer from the codes given below.

Column I | Column II
I. Placoid Scales | 1. Chondrichthyes
II. Ctenoid scales | 2. Osteichthyes
III. Ectoparasites | 3. Hemichordata
IV. Proboscis gland | 4. Cyclostomata

Codes:
  • a)
    1 2 3 4
  • b)
    2 1 4 3
  • c)
    2 1 3 4
  • d)
    1 2 4 3
Correct answer is option 'D'. Can you explain this answer?

Sinjini Choudhury answered
Understanding the Matchings
In this question, we need to match items from Column I with their respective classifications or characteristics from Column II. Here’s an explanation of each item:
Placoid Scales
- These are the scales found in Chondrichthyes, which include sharks and rays.
- Placoid scales are tooth-like structures that provide protection and help reduce turbulence while swimming.
Ctenoid Scales
- These scales are characteristic of Osteichthyes, or bony fish.
- Ctenoid scales have a comb-like edge and are more flexible compared to other types of scales, providing better movement in water.
Ectoparasites
- Ectoparasites are organisms that live on the outside of a host, often feeding on its blood or tissues.
- An example of ectoparasites includes certain species of leeches and lice, which are commonly associated with Hemichordata and other marine organisms.
Proboscis Gland
- This gland is primarily found in Cyclostomata, which includes lampreys and hagfish.
- The proboscis gland is used for feeding and attachment to hosts, particularly in parasitic species.
Matching Codes
- Based on the definitions and classifications:
- I. Placoid Scales → 1. Chondrichthyes
- II. Ctenoid Scales → 2. Osteichthyes
- III. Ectoparasites → 4. Cyclostomata
- IV. Proboscis Gland → 3. Hemichordata
Correct Answer Explanation
The correct matching is represented by option D (1 2 4 3), indicating:
- Placoid Scales are associated with Chondrichthyes (1).
- Ctenoid Scales are associated with Osteichthyes (2).
- Ectoparasites are linked to Cyclostomata (4).
- Proboscis Gland corresponds with Hemichordata (3).
Thus, option D accurately matches each item from Column I to Column II.

One of the following options is not used for explaining atomic radius
  • a)
    coordinate radius
  • b)
    covalent radius
  • c)
    van der waals’radius
  • d)
    metallic radius
Correct answer is option 'A'. Can you explain this answer?

Pooja Mehta answered
Atomic radius
The distance from the centre of the nucleus to the outermost shell containing electrons.
or
The distance from the centre of the nucleus to the point up to which the density of the electron cloud is maximum.

Types of atomic radii
1) Covalent radius
2) Van der waals radius
3)Metallic radius

Metagenesis refers to?

Options:
  • a)
    The presence of different morphic forms
  • b)
    Alternation of generation between asexual and sexual phases of an organism
  • c)
    Occurrence of a drastic change in the form during post-embryonic development
  • d)
    Presence of a segmented body and parthenogenic mode of reproduction
Correct answer is option 'B'. Can you explain this answer?

Shivani Kulkarni answered
Alternation of generation between asexual and sexual phases of an organism
Metagenesis refers to the phenomenon of alternation of generation between asexual and sexual phases of an organism. This term is commonly used in the context of certain invertebrates, such as jellyfish, where the life cycle involves both sexual and asexual reproduction.

Explanation:
- In metagenesis, the organism goes through both sexual and asexual phases during its life cycle.
- The asexual phase typically involves reproduction by budding or fragmentation, leading to the formation of new individuals.
- The sexual phase involves the production of gametes, which fuse to form a zygote that develops into a new organism.
- This alternating pattern of reproduction allows for genetic variation and adaptation to different environmental conditions.
- Metagenesis is a unique reproductive strategy that ensures the survival and success of certain organisms in their respective habitats.
In conclusion, metagenesis is an intriguing biological phenomenon that showcases the diversity and complexity of reproductive strategies in nature.

Which of the following statements correctly describes the presence of the notochord in Urochordata and Cephalochordata?
  • a)
    In Urochordata, the notochord is present throughout the life and extends from head to tail, while in Cephalochordata, it is present only in the larval tail.
  • b)
    In Urochordata, the notochord is present only in the larval tail, while in Cephalochordata, it extends from head to tail region and is persistent throughout their life.
  • c)
    In both Urochordata and Cephalochordata, the notochord is present only in the larval tail.
  • d)
    In both Urochordata and Cephalochordata, the notochord extends from head to tail and is persistent throughout their life.
Correct answer is option 'B'. Can you explain this answer?

Bs Academy answered
In Urochordata, the notochord is present only in the larval tail, while in Cephalochordata, it extends from head to tail region and is persistent throughout their life.

Read the following statements:
(a) Metagenesis is observed in Helminths.
(b) Echinoderms are triploblastic and coelomate animals.
(c) Round worms have organ-system level of body organization.
(d) Comb plates present in ctenophores help in digestion.
(e) Water vascular system is characteristic of Echinoderms.

Options:
  • a)
    (a), (d) and (e) are correct
  • b)
    (b), (c) and (e) are correct
  • c)
    (c), (d) and (e) are correct
  • d)
    (a), (b) and (c) are correct
Correct answer is option 'B'. Can you explain this answer?

EduRev NEET answered
(a) Metagenesis is observed in Helminths: Incorrect. Metagenesis refers to the alternation of generations between asexual and sexual phases, observed in cnidarians, not in helminths.
(b) Echinoderms are triploblastic and coelomate animals: Correct. Echinoderms have three germ layers (triploblastic) and a true coelom.
(c) Round worms have organ-system level of body organization: Correct. Roundworms (nematodes) have an organ-system level of organization.
(d) Comb plates present in ctenophores help in digestion: Incorrect. Comb plates (ctenes) in ctenophores are used for locomotion, not digestion.
(e) Water vascular system is characteristic of Echinoderms: Correct. The water vascular system is a unique feature of echinoderms.
Thus, the correct answer is Option B.

The elements charecterised by the filling of 4 f-orbitals, are:
  • a)
    Alkali metals
  • b)
    Lanthanoids
  • c)
    Alkaline earth metals
  • d)
    Transition elements)
Correct answer is option 'B'. Can you explain this answer?

Rohan Singh answered
The f block elements are the lanthanides and actinides and are called the inner transition elements because of their placement in the periodic table due to their electron configurations. The f orbitals of the electron shell are filled with “n-2.” There is a maximum of fourteen electrons that can occupy the f orbitals.

An object of mass 5 kg is initially moving with a velocity of 10 m/s. An unbalanced force of 30 N is applied to the object in the opposite direction of its motion. Calculate the acceleration of the object.
  • a)
    6 m/s2
  • b)
    2 m/s2
  • c)
    4 m/s2
  • d)
    8 m/s2
Correct answer is option 'A'. Can you explain this answer?

Rishabh Chavan answered
Given:
Mass of the object (m) = 5 kg
Initial velocity (u) = 10 m/s
Force applied (F) = 30 N

To find:
Acceleration of the object (a)

Explanation:

Newton's second law of motion:
The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. It can be expressed as:
F = ma

Calculating the acceleration:
To find the acceleration of the object, we can rearrange the formula as:
a = F/m

Substituting the given values:
a = 30 N / 5 kg
a = 6 m/s^2

Therefore, the acceleration of the object is 6 m/s^2.

Answer:
The correct answer is option A) 6 m/s^2.

A car of mass 1000 kg is moving at a velocity of 20 m/s. Suddenly, the driver applies the brakes, and the car comes to a stop in 4 seconds. What is the magnitude of the average force exerted by the brakes on the car? (Assume no external forces are acting on the car)
  • a)
    5000 N
  • b)
    250 N
  • c)
    1000 N
  • d)
    2000 N
Correct answer is option 'A'. Can you explain this answer?

Anshu Saha answered
Solution:

Given:

Mass of the car, m = 1000 kg

Initial velocity, u = 20 m/s

Final Velocity, v = 0 (since the car comes to a stop)

Time taken, t = 4 s

Acceleration, a = ?

Force, F = ?

Using the kinematic equation,
v = u + at
0 = 20 + a × 4
a = -5 m/s² (negative because the car is decelerating)

Using Newton's second law of motion,
F = ma
F = 1000 kg × (-5 m/s²)
F = -5000 N (negative because the force is acting opposite to the direction of motion)

Taking the magnitude of force,
F = 5000 N

Therefore, the magnitude of the average force exerted by the brakes on the car is 500 N.

Option (a) is the correct answer.

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