Category: Biology Second Paper

There are three types of valves in the heart of roe fish.
(i) Sino-atrial cavity: It lies between the sinus venosus and the atrium.
(ii) Atrio-ventricular chamber: It lies between the atria and the ventricles.
(iii) Ventriculo-bulbus capatica: It lies between the ventricles and the bulbous aorta.

Conus arteriosus is absent in the heart of roe fish. The root of the artery swells to form the bulbus arteriosus. The bulbus arteriosus is not part of the heart as it is not covered by myocardium or pericardium. It delivers blood from the heart to the ventral aorta. Dr. Siddiq Publications

The heart of ruhi fish is located in the pericardial cavity. It is covered by the pericardium. It is called a myogenic heart because the heart muscle in the heart wall produces the heartbeat. The parts of the heart are:
1. Subchamber or sinus venosus: Sinus venosus is a triangular shaped and elastic subchamber. It is thin walled. Blood enters the sinus venosus from the veins, ductus cuveae, and hepatic sinuses. Blood enters the atrium from the sinus venosus. Siddique Publications
2. Atrium: The atrium is the largest chamber of the heart. It is triangular, muscular and thin walled. One end is connected to the ventricles and the other end to the sinus venosus. It collects blood containing CO2 from the sinus venosus and delivers it to the lungs. Siddique Publications
3. Ventricle : Ventricle is a muscular, fleshy and thick walled cavity. One end of the ventricle is connected to the atrium and the other end to the bulbus arteriosus. It is filled with blood containing CO2. Dr. Siddiq Publications
4. Bulbus arteriosus: Conus arteriosus is absent in the heart of roe fish. The root of the artery swells to form the bulbus arteriosus. The bulbus arteriosus is not part of the heart as it is not covered by myocardium or pericardium. It delivers blood from the heart to the ventral aorta. Dr. Siddiq Publications
5. Cardiac valves: There are three types of valves in the heart of roe fish.
(i) Sino-atrial cavity: It lies between the sinus venosus and the atrium.
(ii) Atrio-ventricular chamber: It lies between the atria and the ventricles.
(iii) Ventriculo-bulbus capatica: It lies between the ventricles and the bulbous aorta.

The system through which blood circulates in the body is called circulatory system. The blood circulation of cotton fish is closed. It shows unicyclic or unicyclic blood circulation. Circulation in which O2-rich or CO2-rich blood circulates through the heart in one cycle is called unicyclic or unicyclic circulation. The circulatory system of roe fish consists of four parts. Heart, Arterial System, Venous System and Blood. Dr. Siddiq Publications

Ruhi fish have even/paired and odd/unpaired fins. Each fin has bony fin rays. It has five types of fins.
1. Pectoral fins: Kanko has a pair of pectoral fins on its back. It has 16-19 fin rays. It helps the fish rise to the top of the water.
2. Surface fins: There is a surface fin on the surface of the body. It has 14-16 fin rays. It helps the fish to turn and stop.
3. Class fins: There is a pair of class fins in the middle part of the body. It has 7-9 fin rays. This helps the fish move up and down and stop.
4. Anal fins: There is an anal fin behind the anus on the base of the body. It has 4-7 fin rays. It helps keep the fish stable.
5. Caudal Fin: There is a caudal fin behind the tail. It is bisected and homocircular. It has 19 fin rays. It acts as the main locomotor organ of the fish. Dr. Siddiq Publications

Cycloid cysts are round or oval in appearance and silvery white in color. At its center is the focus or nucleus. It has two types of lines. Circulus line and annulus line. Menstrual line of Aish is called Circulus line. It is short and vague. The annual line of gravity is called annulus line. It’s big and clear. One annulus line is formed every year in a cycloid scale. The month can be determined by calculating the circle line and the year by calculating the annulus line. If there is 1 annulus line in Aish, 1 year is calculated, if there are 2, 2 years. Thus the age of the fish is determined by counting the annulus and circulus lines. Ruhi fish live for a maximum of 10 years. Therefore, there can be maximum 10 annulus lines in its scales. Dr. Siddiq Publications

Fish scales that are round or oval, with growth lines and smooth edges are called cycloid scales. Chemically, fibers are composed of calcium and collagen fibers. During the spring and summer, there is more growth of anise. Cycloid Anish consists of three parts. The parts are-
1. Foreground : The front part of scale is called Foreground. It resides in the inner part of the body and in pockets of the dermis. The anterior fibrous connective tissue is constructed of banana. The longitudinal grooves seen in the tip are called radii. Dr. Siddiq Publications
2. Backyard : The exposed part on the outer side of the anish is called Backyard. It is made of dentin.
3. Side Area: The part on either side of the Aish is called side area.

1. Scales act as the main protective organ of fish.
2. It reduces the water barrier during fish movement.
3. The mucus present in the scales destroys the germs and makes the fish immune to diseases.
4. Lateral waves sense the frequency of the water.
5. Anim plays a role in determining the taxonomy, age, growth rate, life history etc. of fish.

Fish body which is round or oval, covered with hard and thin shell is called fish. The main defense organ of fish is scales. It originates from the dermal layer of the skin. Different types of fish scales are cycloid scales, placoid scales, ganoid scales, tinoid scales etc.

1. By this the fish can determine the pH of the water.
2. It helps the fish to determine the depth of the water.
3. With the help of this line, the fish can sense the turbidity of the water.
4. Receives stimuli from the external environment.
5. It helps to escape from enemies.