SS 3 Biology

Organic Evolution Organic evolution is the sum total of adaptive changes from pre–existing or old forms that has taken place over a long time resulting in diversity of forms, structures and functions among organism. The basis of evolution is that all organisms have pre–existing ancestors. Evidence of evolution Fossil record: A fossil is an impression […]

Social animals are those in which individuals of the same species live together cooperatively in organized communities known as societies (colonies). Examples of social animals are: social insects (like termites, honey bees or wasps, ants etc), wolves, foxes, baboons etc. Characteristics of Social Insects They live together They display division of labour They show distinct

Population is a group of organisms of the same specie living in a specified area within a given period of time. Variation refers to the differences which exist between individuals of the same species Types of variations Morphological variation Physiological variation. Morphological variation is the noticeable physical appearance of individuals of the same species. This

Genetic Terminology Genetics, the scientific study of heredity and variation in all living organisms, was termed by Dilliam Bateson in 1906. Heredity/Inheritance pertains to the passage and manifestation of traits from parents to offspring, accounting for the common resemblances between them. Variation encompasses the dissimilarities existing among parents, offspring, and siblings. Genes are hereditary units

Structure of a Fruit A fruit is a matured fertilized ovary of a flower containing one or more seeds. Contrary to this, some plants do not undergo fertilization for the formation of their fruit. Such fruits are called parthenocarpic fruits e.g. banana and pineapple. Such fruits are seedless. A typical fruit has the following parts

Development of Zygotes in Plants In flowering plants, the process of pollination is followed by fertilization, leading to the development of the zygote. This development eventually transforms the flower into a fruit that encloses the seeds. The male and female sex cells responsible for zygote formation are the pollen grain and the ovule, respectively. The

Female Reproductive System Ovaries: Two oval, cream-coloured structures located in the lower abdomen below the kidneys. These organs produce ova (eggs). Oviducts: Tubes that convey the ova from the ovaries to the uterus. Fertilization typically occurs in the upper portion of the oviducts. Uterus: The uterus is a hollow, muscular organ situated in the lower

In the realm of nature, a state of dynamic equilibrium prevails. When environmental conditions influenced by population dynamics, encompassing both abiotic and biotic elements, are propitious, growth is encouraged. Conversely, when these conditions turn unfavorable, growth is hindered. A constraining element that curbs population expansion is termed a “limiting factor.” The amalgamation of all these

1. Ecology Population: An ecological population refers to a group of individuals of the same species that live in the same area and interact with each other. This concept is fundamental to the field of ecology, which is the study of how organisms interact with each other and their environment. A population is defined by

THE ORGAN OF HEARING Mammals possess a bilateral auditory system consisting of two ears located on each side of the head. The majority of the auditory system is protected within the skull. Its primary functions are hearing and maintaining balance. ANATOMY AND FUNCTIONS OF THE EAR The mammalian ear can be divided into three main

SENSORY RECEPTORS Living organisms have the ability to respond to changes in their environment, known as stimuli. These stimuli can be of various types, including mechanical, electromagnetic, chemical, or thermal. While most cells in an organism’s body are capable of sensing stimuli, certain cells specialize in detecting specific types of stimuli. These specialized cells are

Plant coordination relies on chemicals known as plant hormones. These hormones share similarities with animal hormones in that they: Are required in small amounts to exert their effects Are produced in one part of the plant and transported to other parts to elicit their effects However, plant hormones differ in that they are not produced

What are Hormones? Hormones are chemical substances produced or secreted by endocrine glands, which are ductless glands in the body. They are released into the bloodstream and travel to target organs to exert their effects. Hormones can speed up or slow down biological reactions in the body. They act as chemical messengers, produced in one

STRUCTURE OF THE KIDNEY The mammalian kidney is a reddish-brown, bean-shaped organ located in the posterior end of the abdomen. The right kidney is slightly lower than the left. On cutting a kidney longitudinally, two distinct regions are observed: an outer cortex and an inner medulla. Narrow tubules called urinary tubules (nephrons) pass through these