Structural Organization in Animals: Important Questions

Very Short Answer Questions (1 Mark Questions)

Ques. What is meant by the term ‘cell junctions’?

Ans. Cell junctions are defined as the structures that hold together the adjacent cells of tissue when they are not separated widely by the extracellular material.

Ques. Define endocrine glands.

Ans. Endocrine glands are ductless glands that help in the secretion of hormones directly into the bloodstream.

Ques. List the function of neuroglial cells.

Ans. Neuroglial Cells serve as packing and supporting material between the nerve cells.

Ques. Name the following: 

1. Cells from which thrombocytes are produced
2. A heterochrony gland
3. The functional unit of a muscle

Ans. (a) Megakaryocytic cells

(b) Pancreas

(c) Sarcomere

Ques. Define myoepithelial cells.

Ans. Myoepithelial cells are those cells that show the peculiar characteristics of both muscles and epithelial tissues.

Ques. What is synthesized by the fibroblasts?

Ans. Collagen and elastin proteins are synthesized by the fibroblast in areolar tissues.

Ques. List the two fundamental types of smooth muscles.

Ans. The two fundamental types of smooth muscles are: 

• Single unit smooth muscle
• Multi-unit smooth muscle

Also check: Difference between Red Muscle Fibres and White Muscle Fibres

Ques. What do you understand by ‘double circulation’?

Ans. Double circulation is defined as the process in which the blood passes twice through the heart to move through the body.

Ques. Give an example of inverted sugar. Why is it named so?

Ans. An example of inverted sugar is Sucrose. It is named so because the hydrolysis inverts the rotation of plane-polarized light.

Ques. Give the full form of ESR and EDTA.

Ans. ESR stands for Erythrocytes Sedimentation Rate whereas EDTA stands for Ethylene Diamine Tetra Acetic Acid.

Short Answer Questions (2 Marks Questions)

Ques. List down the major functions of haemoglobin.

Ans. The major functions of haemoglobin are listed as follows:

• Haemoglobin is vital as it is an oxygen carrier from the lungs to the tissue in the form of oxyhaemoglobin. There are around 1.33 ml of oxygen carried by each molecule of haemoglobin.
• It plays an important role in the transport of CO₂ as Carbaminohemoglobin from tissue to the lungs. Haemoglobin transports about 23 percent of CO₂ back to the lungs.

Also check: Types of White Blood Cells

Ques. Define Oligodendrocytes along with their functions.

Ans. Oligodendrocytes are classified as a type of neuroglia cells that hold together the neurons in position in the central nervous system. They spirally wrap around the nerve fibres and form a myelin sheath in the central nervous system in the absence of Schwann cells.

Ques. Which tissue forms the outermost exposed surface of the human skin. Give any two advantages of this tissue.

Ans. Keratinised squamous epithelium is the specific tissue that forms the outermost exposed surface of the human skin. This tissue contains insoluble protein-keratin which is impervious to water and thus helps in preventing the loss of water. Also, it offers protection to the skin against friction, injury, mechanical pressure and water loss.

Ques. How is clotting in blood prevented in the blood banks?

Ans. Various anticoagulants such as sodium oxalate, sodium citrate and EDTA (Ethylene diamine tetraacetic acid) are used in blood banks in order to prevent coagulation by removal of calcium ions.

Blood clotting is also prevented by removing the free calcium ions from the whole blood as the calcium ion is an essential requirement in several stages of the coagulation mechanism.

Ques. What are the functions of platelets in the human body?

Ans. In case of any injury to any tissue, the platelets disintegrate and liberate a thromboplastin which deals with the activation of prothrombin to thrombin. They are sticky in nature and they get adhered to the rough surfaces of foreign bodies like bacteria. This type of response helps in increasing bodily defence as leukocytes can phagocytize these microbes more conveniently.

Read about: Difference Between RBC and WBC

Ques. Site the main difference between the blood of an earthworm and a man?

Ans. The colour of the blood of an earthworm is red because of the haemoglobin that is dissolved in plasma. Also, in earthworms, the corpuscles are colourless and nucleated. Similarly, the blood of a man is also red but haemoglobin is dissolved in RBCs. The corpuscles in human blood are denucleated and biconcave disc-like.

Ques. What is the main excretory organ in the cockroach? State its function in the process of excretion.

Ans. Malpighian tubules are the main excretory organ in the cockroach. In cockroaches, each malpighian tubule is lined by ciliated, glandular cells with a brush border. The nitrogenous waste product is absorbed and converted into uric acid by them through various biochemical processes. Then, the hindgut is used to excrete the uric acid. Apart from the malpighian tubules, the fat bodies, nephrocytes, cuticles and urecose glands also help in the process of excretion in cockroaches.

Ques. Elaborate on the female reproductive system in the cockroach.

Ans. The female reproductive system in the cockroach consists of two large ovaries lying laterally in the fourth, fifth and sixth segments. Each of the two ovaries is made up of a group of eight ovarian tubules containing a chain of developing ova.

The oviducts in each ovary combine into a single median oviduct that is also called the vagina that opens into the genital chamber. A pair of branched, collateral glands, i.e, female accessory glands, open into the dorsal side of the genital chamber.

Ques. Describe the interaction of frogs with mankind?

Ans. The interaction of frogs with mankind can be described in the following manner: 

• Frogs are useful to man as they eat up insects and thus, protect the crop.
• Frogs are used as experimental material in the fields of teaching and research.
• The muscular legs of the frog are consumed as food by man in some parts of India as well as various other countries.

Check out: Female Reproductive System

Long Answer Questions (3 Marks Questions)

Ques. Describe the male reproductive organs in the cockroach in detail.

Ans. The male reproductive organs of a cockroach consist of a pair of testes, each lying on each lateral side in the 4th-5th abdominal segments. Vas deferens, a thin tube that arises from each testis, opens into the male gonopore located ventral to the anus. In the 6th-7th abdominal segments, a mushroom-shaped gland is present that functions as an accessory reproductive gland.

Chitinous asymmetrical structures represent the external genitalia, surrounding the male gonopore, at the end of the abdomen, called male gonapophysis or phylloxera. The sperms are attached together in the form of bundles which are called spermatophores and are stored in seminal vesicles.

Male Reproductive System of Cockroach

Read More: Male and Female Reproductive Organs

Ques. Give reasons for the following statements: 

1. A transparent nictitating membrane is there on the eyes of a frog.
2. The first finger of a male frog is usually swollen.
3. The skin of a frog is usually moist and slippery.
4. Webs are present in between the toes of a frog.

Ans. The reasons for the above-mentioned statements are as follows:

(i) Nictitating membrane is present in the eyes of a frog to protect them when they undergo mud during hibernation, aestivation and swimming.

(ii) The first finger in a male frog is swollen in the form of a copulatory pad in order to hold up the female frog firmly during copulation.

(iii) The reason why the skin of the frog is moist and slippery is so that it performs cutaneous respiration as well as slips away from the grip of predators.

(iv) The webs are present between the toes of a frog as they act as paddles when the frog is swimming.

Read More: Difference Between Aestivation and Hibernation

Ques. What are the three main types of respiration in the frog? What is the procedure for respiration in frogs during hibernation?

Ans. There are three main types of respiration in a frog:

1. Cutaneous Respiration
2. Buccal Respiration
3. Pulmonary Respiration

The skin of the frog is moist, slimy and highly vascularized which is very useful for the process of respiration in hibernation and aestivation. The oxygen present in the atmosphere enters the thin film of skin moisture from where it goes to the blood capillaries of the skin of the frog. Then, the oxygen dissolves with the blood and passes to the different organs of the body. The carbon dioxide that is formed in the body is carried by the blood capillaries to the skin from where it diffuses out into the air.

Ques. List down the functions of each of the following:

1. Ureters in frog
2. Malpighian tubules
3. Body wall in the earthworm

Ans. (a) Ureters in Frog: Ureters in a frog carries sperms and excretory waste to the cloaca. They also carry the ova in frogs.

(b) Malpighian Tubules: Each of the malpighian tubules is lined by glandular cells that help to carry out the process of excretion. The glandular cells that are present help to absorb the excretory materials which are then converted into uric acid. The uric acid is then released out through the hindgut.

(c) Body Wall in Earthworm: The body wall of an earthworm comprises basal cells, receptor cells and gland cells. It provides support and the cells are involved with the secretion of mucus to keep the skin moist. The muscles are useful to provide strength and rigidity.

Read About: Amphibia

Ques. What are the types and functions of nephridia in an earthworm?

Ans. Nephridia are defined as a series of tube-shaped coiled organs within an earthworm's body that are used to excrete waste.

Types of Nephridia

• Septal Nephridia
• Pharyngeal Nephridia
• Integumentary Nephridia

Functions of Nephridia

• Nephridia helps in the regulation of the composition and volume of body fluids.
• It acts as a funnel that is used to collect excess fluid from the coelomic chamber.
• This organ connects to the tubular parts of the nephridium and the waste is given out to the surface through a pore.

Also check: Phylum Annelida

Ques. Name and explain the different cell junctions found in tissues.

Ans. The different cell junctions found in tissues are:

• Tight Junctions: They help to hold the plasma membrane of adjacent epithelial cells close to each other.
• Gap Junctions: These junctions facilitate the exchange of chemicals between adjacent cells.
• Adhering Junctions: These junctions help in connecting the neighbouring cells together.

Very Long Answer Questions (5 Marks Questions)

Ques. List down the various functions of epithelial tissue in detail.

Ans. The various functions of epithelial tissue are described as follows:

• Protection: Epithelial tissue protects the underlying or overlying soft tissues against wear and tear due to heat, injury, chemicals, viruses, bacteria, etc.
• Absorption: Epithelial tissue helps in the absorption of the digestive food, especially with columnar cells of the intestine.
• Secretion: The glandular epithelial cells that line the inner cavities help in the secretion of various substances like mucous, enzymes and hormones which are essential for the metabolic activities of the body.
• Excretion: The epithelial cells present in the kidney tubules and sweat glands help in the excretion of waste material from the body.
• Sensation: In the epithelial cells of the retina, olfactory organs and nasal chamber, the nerve ending receive the stimuli from the external atmosphere and transfer them to the brain for interpretation.

Read More: Sense Organs

Ques. Define connective tissues and mention the important functions performed by them.

Ans. Connective tissues are a special kind of tissues that are mesodermal in origin and formed of matrix, fibres and cells. These tissues comprise the extracellular ground substance and fill up the intercellular spaces between the cells.

Connective tissues perform various functions in the body of an organism which is as follows: 

• Connective tissues help in binding one tissue or organ to another and act as a strong elastic rope providing the skeletal support and shape to the body. 
• It helps in packing material for almost all the organs.
• The connective tissues protect the vital organs of the cranial and thoracic cavities, deep blood vessels and nerves from numerous mechanical injuries.
• The adipose connective tissue is used for the storage of fat and represents stored energy.
• Connective tissues provide defence against foreign material and organisms like bacteria.

Ques. What are the three classes of proteins in plasma? Explain the functions performed by them.

Ans. The three major classes of proteins found in the plasma are: 

1. Albumin
2. Globulins 
3. Fibrinogen

The functions performed by the plasma proteins are: 

• Normally, plasma proteins have an osmotic effect of 25 mm Hg. Therefore, they influence the exchange of fluid between blood and tissue spaces.
• Plasma proteins especially globulins are considered to be responsible for the viscosity of blood which helps in maintaining peripheral resistance and arterial blood pressure for the proper and efficient functioning of the heart.
• Plasma proteins act as buffers that help to maintain the acid-base balance.
• Albumin and globulin proteins are used for retaining water in the blood plasma by their osmotic effects. Their deficiency in the body leads to oedema.
• Plasma proteins are useful for the transportation of certain substances like hormones, enzymes, iron and copper etc. in the blood.
• Plasma proteins are essential for the distribution of heat uniformly all over the body.

Ques. Elaborate briefly on the blood vascular system of the cockroach.

Ans. A cockroach basically has an open circulatory system. The blood of a cockroach is colourless and contains plasma with colourless cells, the leucocytes. The blood does not contain haemoglobin in a cockroach and thus plays no role in respiration

The heart of a frog is thirteen chambered which is a long, narrow, muscular and tube-like structure. Of the total 13 chambers of the heart, the three chambers lie in the thorax and ten in the abdomen. The posterior end is closed and the anterior end is continued forwards as the anterior aorta and opens into a haemocoel in the head.

A small hole called Ostia is present on the posterior side of each chamber. This hole is guided by valves to allow blood to flow only in one direction i.e., from the haemocoel to the inner chamber of the heart. All the visceral organs of a cockroach are bathed in blood. Plasma, a colourless liquid part, contains many corpuscles called haemocytes.

Open Circulatory System of Cockroach

Read More: Blood Circulatory System

Ques. Explain the reproductive organs of an earthworm with a labelled diagram.

Ans. The earthworm is a hermaphrodite, i.e, it is bisexual. An earthworm has both the testes and ovaries in the same individual. There are two testes that are present in the 10th and 11th segments. There are ducts that arise from the testes that are called vasa deferentia. These ducts run-up to the 18th segment where the ducts join the ventral side of the 17th and 19th segments.

The spermatic and prostate duct open to the exterior through a pair of male genital pores on the ventrolateral side of the 18th segment. In each of the 6th to 9th segments, the spermathecae are found. There are 4 pairs of these that receive and store spermatozoa during copulation.

There are two ovaries that are attached at the intersegmental septum of the 12th and 13th segments. Beneath the ovaries, ovarian funnels are found which continue into oviducts, join together and open on the ventral side as a single female genital pore on the 14th segment.

Reproductive Organs of Earthworm

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