NCERT Solutions for Class 11 Science Biology Chapter 7 - Structural Organisation In Animals

Answer:

The Squamous epithelium is found in the walls of blood vessels and air sacs of lungs. They are made of a single thin layer of flattened cells with irregular boundaries. They are responsible for forming diffusion boundaries.
Hence, the correct answer is option C.

Answer:

Adipose tissue is a type of loose connective tissue and are located beneath the skin. The cells of adipose tissue are specialised for fat storage.
Hence, the correct answer is option b.

Answer:

Muscle is not a connective tissue. Their are four types of tissues in a human body-epithelium, connective, muscle and nervous tissue. Bone, cartilage and blood are a type of connective tissue.
Hence, the correct answer is option d.

Answer:

Setae are s-shaped rows present in each body segments of the earthworm except the first, last and clitelium. They are embedded in the epidermal pits in the middle of each segment.
Hence, the correct answer is option D.

Answer:

Each ovary in a female cockroach is formed of a group of eight ovarian tubules or ovarioles that contains a chain of developing ova. The baby cockroach is called nymph. Male cockroaches bear a pair of short, thread-like anal styles that are absent in females. They are uricotelic.
Hence, the correct answer is option c.

Answer:

Correct Match:
 

Answer:

Correct Match:
 

Answer:

Correct Match
 

Answer:

Correct Match:
 

Answer:

The 14th-16th segment of a mature a earthworm is covered by a prominent dark band of glandular tissue called clitellum.

Answer:

Sclerites are the hardened plates present in each segment of the exoskeleton of cockroach. They are joined to each other by a thin and flexible articular membrane.

Answer:

The baby cockroach is called nymph. They look very similar like adults. They grow by moulting four about 13 times to reach the adult form.

Answer:

Male frogs are distinguished from the female frogs by the presence of sound producing vocal sacs and a copulatory pad present on the first digit of the fore limits.

Answer:

In frogs, external fertilisation takes place in water. The development of frogs involves a larval stage called tadpole and it undergoes metamorphosis to form an adult.

Answer:

Metameres is the scientific term given to the body segments of earthworms.

Answer:

The smooth muscle fibres are tapered at both the ends and do not show any situations. They are involuntary in nature as their function is not directly controlled. They are found in the walls of internal organs such as blood vessels, stomach and small intenstine.

Answer:

Their are three types of cell junctions found in tissues such as -
(i) Tight junction: This junction help to stop the substances from leaking across a tissue.
(ii) Adhering junction: This junction performs cementing to keep neighbouring cells together.
(iii) Gap junction: This junction facilitate the cells to communicate with each other by connecting the cytoplasm of adjoining cells. It is done for rapid transfer of ions, small and big molecules.

Answer:

The two identifying features of an adult male frog are the presence of sound producing vocal sacs and a copulatory pad present on the first digit of the forelimbs.

Answer:

Hypopharynx is a median flexible lobe that act as a tongue. It lies within the cavity enclosed by the mouthparts. Hypopharynx is a mouthpart of cockroach and is comparable to the tongue of humans.

Answer:

The correct order of organs of the digestive system of the frog are:
Mouth
    ↓
Buccal cavity
    ↓
Oesophagus
    ↓
Stomach
    ↓
Intestine
    ↓
Rectum
    ↓
Cloaca
    ↓
Cloacal aperture
 

Answer:

Cutaneous respiration: When gaseous exchange occurs through the skin.
Pulmonary respiration: When gaseous exchange occurs through the lungs.
Cutaneous respiration takes place when the frog is in water while pulmonary respiration takes place when the frog is on land.

Answer:

The special venous connection between liver and intestine of frog is called hepatic portal system.
The special venous connection between the kidney and lower parts of the body in frog is called renal portal system.

Answer:

Hepatic caecae are 6-8 narrow and hollow ring-like blind tubules that are present at the junction of foregut and midgut in the digestive tract of the cockroach. These are lined up by glandular cells that secretes various digestive enzymes and aids in digestion of food.

Answer:

Frogs are beneficial for mankind because they eat insects and also provide protection to the crop. They maintain ecological balance because they serve as an important link of food chain and food web in the ecosystem. The muscular legs of the frog are used as food by human in some countries.

Answer:

Sponges are multicellular animals and their body is made of thousands of cells but these cells do not perform function in coordination with each other. They work independently and their is no division of labour as observed in tissue-level organization.

Answer:

In this given chain, tissue is missing. It is-
Cell
   ↓
Tissue
   ↓
Organ
   ↓
Organ system
Tissue level of organization is the first level of organization. It shows division of labour. Tissues play an important role in structural organization of animals. Tissues are formed from a group of cells that perform specialized functions.

Answer:

The stratified epithelium is made up of more than one layer or multi-layered cells. This epithelium has limited role in secretion and observation. They provide protection against chemical and mechanical stresses. They cover the dry surface of the skin.

Answer:

Gap junctions facilitate the cells to communicate with each other by connecting the cytoplasm of adjoining cells. It is done for rapid transfer of ions, small and big molecules.

Answer:

Blood, bone and cartilage are specialized connective tissue. As, they provide structural framework to the body. They also help in the transportation of various substances. They are responsible for binding and connection of different tissues and organs.

Answer:

Neurons are called excitable cells because neuronal membranea are in a polarized state. The neurons become excited when different ions interact with the neuronal membrane to change their polarization. The ability of a nerve cell to become polarized and depolarized plays an important role in the transmission of nerve impulse. The special feature of neuron membrane is their ability of excitability and conductivity.

Answer:

Earthworms are known as 'Friends of farmer' because they make burrows in the soil to make it porous. This helps in respiration and penetration of the developing plant roots. Vermicomposting is the process of increasing the fertility of soil by the earthworms. Earthworms are also used as a bait in fishing.

Answer:

The dorsal surface of the body of earthworm is marked by a dark median mid dorsal line along the longitudinal axis of the body, whereas the ventral surface of the body is differentiated by the presence of genital openings (pores). Setae are also not found on the dorsal surface.

Answer:

a. The given statement is wrong.
As, a pair of male genital pores are present in the earthworm.

b. The given statement is correct.
Setae is a s-shaped chitinous ring found in the each segment of earthworm. They help in locomotion

c. The given statement is incorrect.
The muscular layer in the body wall of an earthworm is composed of two muscle layer-circular and longitudinal.

d. The given statement is correct.
Typsole is the internal median fold of dorsal wall that increases the effective area of observation in the intestine.

Answer:

Nephridia are excretory organs occurs as a segmentally arranged coiled tubules.
They are of three types:
(i) Septal nephridia: They are present on both the sides of intersegmental septa from segment 15 to the last. It opens into intestine.
(ii) Integumentary nephridia: They are attached to the linning of the body wall of 3rd segment to last. It opens on the body surface.
(iii) Pharyngeal nephridia: They are present in the form of three paired tufts in the 4th, 5th and 6th segments.
Nephridia are responsible for the regulation of the volume and composition of the body fluids.
 

Answer:

Answer:

a. In cockroach grinding of food particle is performed by gizzard.
b. Malpighian tubules help in removal of  excretory products from haemolymph .
c. Hind gut of cockroach is differentiated into ileum, colon and rectum.
d. In cockroach blood vessels open into spaces called haemocoel.

Answer:

(i) Cockroach have compound eyes that are situated at the dorsal surface of the head.
(ii) Each eye of cockroach consists of about 2000 hexagonal ommatidia (visual unit) that helps them to receive several images of an object.
(iii) They have mosaic vision with more sensitivity but less resolution and is being common during night. Thus, called nocturnal vision.

Answer:

Frogs do not have a constant body temperature as their body temperature varies with the ambient temperature. They are called cold-blooded animals or poilkilotherms. They have an ability to change the colour of their body and this helps them to hide from their enemies (camouflage). The protective colouration is called mimicry. Frogs are not seen during summer and winter season. During this period, they take shelter in deep burrows to protect themselves from extreme heat and cold. This process is known as aestivation (summer sleep) and hibernation (winter sleep).

Answer:

Answer:

Answer:

Answer:

Cardiac muscle tissue:
It is a heart muscle tissue or contractile tissue. It is present only in the heart.

• The cell junctions get fused with the plasma membrane of cardiac muscle cells and make them stick together.
• The communication junctions or intercalated discs at some fusion point allow the cells to contract as a unit. As one cell receives signal for contraction and its neighbours are also stimulated for contraction.

Answer:

On the basis of structural modification of the cells, simple epithelium tissue is categorised into three types:
Squamous, Cuboidal, Columnar.

(i) Squamous epithelium:
a) It is composed of a single thin layer of flattened cells and have irregular boundaries.
(b) They are present in the walls of blood vessels and air sacs of lungs.
(iii) They are involved in forming diffusion boundaries.

(ii) Cuboidal epithelium:
(a) It is made of a single layer of a cube-like cells.
(b) It is found in ducts of glands and tubular parts of nephrons in kidneys.
(c) Their main function is secretion and absorption.

(iii) Columnar epithelium:
(a) It is made of single layer of tall and slender cells and their muscles are located at the base.
(b) Microvilli are present on the free surface.
(c) They are found in the lining of stomach and intestine
(iv) They help in secretion and absorption.

Answer:

(i) They are most abundant and widely distributed in the body of complex animal.
(ii) They perform a special function of linking and provide support to other tissues or organs of the body.
(iii) Cells of this tissue secretes fibres (except in blood), of structural proteins called collagen or elastin.
(iv) These protein fibres provide strength, elasticity and flexibility to the tissue.

Difference between bone and cartilage
 

Answer:

Their is mutual exchange of sperm take place between two worms during mating.
One earthworm find another earthworm and they mate juxtaposing opposite gonadal opening.
At this point, they are exchanging packets of sperms called spermatophores.
Mature sperm and egg cells as well as nutritive fluid are deposited in coccoons produced by the gland cells of clitellum.

• Fertilisation and development takes place within the cocoons which then slips off the worm and is deposited in or on the soil.
• The cocoon holds the worm embryos and after about 3 weeks, two to twenty baby worms are produced by each cocoon with an average of four.
• Direct development occurs in earthworm i.e., there is no larva formed.

Answer:

The alimentary canal of cockroach is present in the body cavity. It is divided into three region:
(i) Foregut:
In foregut, the mouth opens into a short tubular pharynx and it leads to a narrow tubular passage called oesophagus.
The oesophagus opens into a sac-like structure called crop. It is used for food storage.
The crop is followed by gizzard or proventriculus that has an outer layer of thick circular muscles as well as a thick inner cuticle. It forms six highly chitinous plate called teeth.
The food particles are grinded by gizard and the whole foregut is lined by cuticle.
(ii) Midgut: At junction of foregut or midgut, 6-8 blind tubules called hepatic or gastric caeca is present.
The hepatic caeca secretes digestive juice.
(iii) Hindgut: Another ring of 100-150 yellow coloured thin filamentous structure called Malphigian tubules are present at the junction of midgut and hindgut.

• Malphigian tubules help in the removal of exertory products from haemolymph.
• It is broader than midgut and is differentiated into ileum, colon and rectum that open out through anus.

Answer: