Category: Biology Second Paper

Archeopteryx appeared 14.7 million years ago. It has features of both bird and reptile classes. Its features are-

1. Reptilian traits

(i) Archeopteryx 20 vertebrae long like reptiles.

(ii) Their bones are thick and heavy.

(iii) They have teeth in their jaws.

(iv) Their bodies consist of dry scales.

(v) They have claws on their wings.

 

2. Characteristics of birds

(i) Body structure of Archeopteryx is similar to bird.

(ii) Their bone structure is similar to that of birds.

(iii) They have wings like birds.

(iv) Their bodies have bird-like tails and feathers.

(v) Their lips have turned into bird-like beaks.

The characteristics of Archeopteryx show that it has characteristics of the Reptilia and Avis classes. Archeopteryx is therefore said to be the link connecting the two classes.

A living organism is called a living fossil if the characteristics of a fossil animal of the past match the characteristics of a living animal of the present. Fossil organisms survive on Earth in morphologically and physiologically unchanged forms.

Characteristics of Platypus

(i) Body of platypus is covered with hair.

(ii) They lay eggs containing yolk and the eggs hatch.

(iii) They have active mammary glands.

(iv) Their cubs drink mother’s milk.

(v) T-shaped thoracic skeleton of platypus.

The features of the platypus are very similar to those of past fossil animals. Hence the platypus is called a living fossil.

(i) Vertebrate brain: The brain of vertebrates has evolved. Brains are enlarged in fish, amphibians, reptiles, avius ​​and mammals. The structure of the cerebral hemispheres and cerebellum is complex.

(ii) Vertebrate heart: The heart of vertebrates has undergone gradual evolution. The heart of fish is two-chambered, the heart of amphibians is three-chambered, the heart of reptiles is partially four-chambered, and the heart of birds and mammals is fully four-chambered. The heart has progressed from simple to complex.

(iii) Homologous organs: Organs which are similar in function but different in structure and origin are called homologous organs. For example, the wing of a bird and the wing of a butterfly are symmetrical organs.

(iv) Homologous Organs: Organs which are structurally similar are called homologous organs. Wings of birds and bats, hands of humans, front legs of horses and flippers of whales are related organs.

(v) Peripheral organs: Organs which are not functional are called peripheral organs. Such as ear muscles, pineal gland, coccyx and body hair.

(i) Lamarckism was introduced by Lamarck. Darwin introduced the theory of Darwinism.

(ii) In Lamarckism the body changes under the influence of the environment and by the organism’s own efforts. In Darwinism, organisms change spontaneously.

(iii) Natural instinct is not recognized in Lamarckism. Darwinism recognizes natural instinct.

(iv) In Lamarckism organisms can develop new traits for their own needs. In Darwinism, nature forms the organism.

(v) According to Lamarck, organisms live in harmony with nature. According to Darwin, organisms survive by winning the struggle for life.

(vi) Lamarckism is not acceptable in scientific circles. Darwinism is acceptable to scientists.

 

(i) All selection in organisms is not natural.

(ii) Natural selection is unable to explain the presence of passive organs in any organism.

(iii) How appropriate variation is derived is not stated.

(iv) Unable to explain that variation occurring in germ cells is heritable.

(v) The possibility of new species arising from differentiation between different members of the same species is very low.

(i) Body Fossils: Fossils of bodies and body parts of dinosaurs have been found in petrified or sedimentary rock layers. By examining these fossils, it has been confirmed that dinosaurs existed on earth.

(ii) Skeletal Fossils: Bones, skeletons and hard parts found in rock layers have been proved to be dinosaur fossils.

(iii) Fossils in sediments: The existence of dinosaurs has been confirmed from fossils of eggshells and faeces found in rock strata.

(iv) Footprints: Evidence of the existence of dinosaurs has been found by examining the footprints found on the bedrock by carbon radiation.

According to Lamarck’s theory of evolution, the early male giraffe had a shorter neck and front legs than a horse. They eat grass and leaves of small plants. Due to various reasons, the amount of grass on the ground decreases and then they start eating the leaves and branches of tall trees. Later it starts eating the leaves of higher trees. In this way, the giraffe’s neck becomes longer due to eating the leaves of tall trees. It is the nervous system of the giraffe that makes it eat leaves with its neck raised. Giraffe’s neck lengthened according to his wishes and needs. Later, the length of the neck increased with each other. Modern long-necked giraffes evolved from short-necked ancestors. The topic of Lamarckism in the evolution of Giraffe is-

(i) Under the influence of endogenous forces organisms can cause growth of their organs.

(ii) Environment has a direct effect on organisms.

(iii) Development of any organ of an organism depends on its use and disuse.

(iv) Acquired qualities of organisms are transmitted from generation to generation.

Anti-Rhesus antibody called anti-D has now been discovered. Anti-D antibody rhesus is introduced into the body of the negative mother within 72 hours of birth.

1. Blood transfusion: If a patient with Rh negative (Rh-ve) blood group receives Rh positive (Rh+ve) blood, there is no problem the first time. However, Rh antibodies develop in his blood within the second week. Later, if the patient receives Rh positive (Rh+ve) blood, his red blood cells are destroyed due to Rh antibodies. Patients may die with various complications.
2. In pregnancy: If a woman with Rh negative (Rh-ve) blood is married to a man with Rh positive (Rh+ve) blood, the first child will be Rh positive (Rh+ve). During this time, Rh antibodies are created in the mother’s blood. Later during pregnancy, the previously produced Rh antibodies are transferred from the mother’s blood to the fetus through immortality. In this the red blood cells of the fetus are destroyed and the child dies.

In 1940, biologists Karl Landsteiner and A. M. Wiener discovered an antigen from the red blood cells of a rhesus monkey (Macaca mulatta). It is called Rh factor or Rhesus factor or antigen factor. Later they discovered the Rhesus factor from human red blood cells. If Rh factor is present in human red blood cells then it is called Rh positive or Rh+ve and if it is absent it is called Rh negative or Rh-ve.

15% of Americans, Canadians, Europeans and Caucasians are Rh-positive. 18-30% of the Berbers and Bedouins of Africa and 25-30% of the Basques of the Pyrenees carry the Rh trait. A very low Rh trait is observed in Bengalis.