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Sexual Reproduction Introduction The sexual mode of reproduction comprises the process of combining DNA from two different individuals. There are two germ-cells (responsible for producing a new organism); one is large and contains the food-stores whereas the other one is smaller and likely to be motile. The motile germ-cell, normally, is known as the ‘male gamete’ and the germ-cell containing the stored food is known as the ‘female gamete.’ Sexual Reproduction in Flowering Plants As shown in the image given below, flowers have different parts, such as sepals, petals, stamens, and carpels. Among these, stamens and carpels are the reproductive parts and contain the germ-cells. Stamen is the male reproductive part, which produces pollen grains (yellowish substance). Carpel, which is present in the center of a flower, is the female reproductive part. Carpel is made of three parts. The bottom part, which is swollen, is the ovary; the middle part, which is elongated, is known as the style; a...

HOW DO ORGANISMS REPRODUCE? Introduction A basic occurrence in reproduction is the creation of a DNA copy; to produce copies of the DNA, cells use chemical reactions. The DNA in the cell nucleus is actually the information source for creating proteins. Likewise, if the information is changed here, then different proteins will be created. And, these different proteins will eventually lead to altered the body designs. DNA copies that generated would be similar, but may not be identical to the original. And, because of these variations, the new born cells are slightly different. Further, the consistency of DNA copying during reproduction process is significant for the maintenance of body design and features. Modes of Reproduction Used by Cell Organisms The modes by which various Cell Organisms reproduce depend on their body designs. However, it is broadly categorized as: Asexual Reproduction & Sexual Reproduction Let’s discuss each of them in Brief: Asexual Reproduction Asexual Reprod...

Harmones in animal Introduction Human body has different glands (as shown in the image given below) that secret Hormones (liquid substance), which are essential for the different body functions. Adrenaline Hormone is secreted from the adrenal glands. It is secreted directly into the blood and then carried to different parts of the body. On the other hand, plants have hormones that control and regulate their directional growth. Iodine is essential for the thyroid gland that makes thyroxin hormone. Further, Iodine is an essential element for the synthesis of thyroxin. Deficiency of Iodine, which might cause goiter. The term “goiter” refers to the abnormal expansion of the thyroid gland (resulting into swollen neck). Thyroxin Hormone regulates carbohydrate, protein, and fat metabolism in the body and provide the best balance for body growth. Growth hormone, which is secreted by the pituitary gland, regulates growth and development of the body. The deficiency of growth hormone in childhood...

CONTROL AND COORDINATION Introduction In multicellular organisms, following the general principles of body organization, some specialized tissues are used to provide the control and coordination activities. Nervous System Nervous system is specialized system that provide control and coordination in animals. All information, coming from our environment is detected by the specialized tips of some nerve cells, which are usually located in sense organs. The information, acquired at the end of the dendritic tip (shown in the image given below) of a nerve cell, sets off a chemical reaction that creates an electrical impulse. This (electrical) impulse, which travels from the dendrite tip to the cell body, and then along the axon to its end of the axon, sets off the release of some chemicals. These chemicals cross the gap, or synapse, and create a similar electrical impulse in a dendrite of the next neuron (see the image given below). Likewise, the nervous tissue is made up of an organized net...

EXCRETION Introduction The biological process that involves in the removal of the harmful metabolic wastes from the human body is known as excretion. Different species (organisms) use different processes for the excretion. E.g. many unicellular organisms remove their wastes by simple diffusion process from the body surface into the surrounding water. Excretion in Human Beings The body parts that the excretory system (of human beings) includes are: A pair of kidneys A pair of ureters A urinary bladder A urethra Kidneys are located in the abdomen (see the image given below), one on either side of the backbone. Urine that produced in the kidneys passes through the ureters into the urinary bladder where it gets stored until released through the urethra. On the other hand, plants have completely different process for excretion than those of animals. Oxygen (released in the day-time) itself can be considered as a waste product generated during photosynthesis. Many plant waste products are st...

TRANSPORTATION IN PLANTS ( Plants Transportation ) Introduction The plants have low energy needs, as they use relatively slow transport systems. Plant transport systems move energy from leaves and raw materials from roots to all their parts. The xylem (tissue) moves water and minerals obtained from the soil to all other parts of the plants. The phloem (tissue) transports products of photosynthesis from the leaves (where they are synthesized) to other parts of the plant. Movement of Water in Plants Water moves into the root from the soil and then steady it moves into the root xylem, creating a column of water, which is progressively pushed upwards. Evaporation of water molecules from the cells of a leaf creates a suction process, which pulls water from the xylem cells of roots; this process keeps going on. The loss of water in the form of vapor from the leaves (i.e. aerial parts) of the plant is known as transpiration. Transpiration, likewise, helps in the absorption and upward movement...

Transportation in Humans Introduction The blood is responsible to transport food, oxygen, and waste materials in human bodies. Blood usually consists of a fluid medium known as plasma where the cells remain suspended. Plasma is responsible to transport food, carbon dioxide, and nitrogenous wastes in dissolved form. However, oxygen is carried by the red blood cells. Many other substances such as salts, are also transported by the blood. A Human Heart The heart is one of the most significant muscular organs of a human body. As both the oxygen and the carbon dioxide get transported by the blood; so, to avoid the oxygen-rich blood from mixing with the blood containing carbon dioxide, the heart has different chambers. Oxygen-rich blood from the lungs comes to the thin-walled upper chamber of the heart on the left, i.e. the left atrium (see the image). When it is collecting the blood, the left atrium relaxes; however, while the next chamber, i.e. the left ventricle expands, then it (left atr...

VERTEBRATA Introduction The organisms of this kingdom have a true vertebral column and the internal skeleton structure. Classification of Vertebrata Vertebrates are further classified as: Pisces Amphibia Reptilia Aves Mammalia Let’s discuss each of them in brief: Pisces The organisms of this group are typically different types of fishes. Fishes can live only in water. The skin fish is covered with scales/plates. Fish use oxygen dissolved in water by using gills The tail of fish helps in their movements. Fishes are cold-blooded organisms and their hearts have only two chambers. Fishes lay eggs. Amphibia The organisms of amphibia have mucus glands in the skin, and they have three-chambered heart. Amphibian can live in water as well as on land. The organisms of amphibian respire through either gills or lungs. The organisms of amphibia lay eggs. Reptilia The organisms of this group are cold bolded. The organisms of reptilia lay eggs with tough coverings. Aves The organisms of Aves group ar...

ANIMALIA KINGDOM Introduction The organisms, which are eukaryotic, multicellular, and heterotrophic, are categorized as Animalia kingdom. The organisms of Animalia kingdom have no cell-wall. Most of animals of Animalia kingdom are mobile. Classification of Animalia Kingdom Based on the extent and type of the body design differentiation, Animalia kingdom classified as: Porifera Coelenterata Platyhelminthes Nematoda Annelida Arthropoda Mollusca Echinodermata Protochordata Vertebrata Pisces Amphibia Reptilia Aves Mammalia Let’s discuss each of them in brief: Porifera The literal meaning of ‘porifera’ is the organisms with holes. The organisms of porifera are non-motile and attached to some solid support. The examples of this group are Sycon, Spongilla, Euplectelia, etc. Coelenterata Organisms of coelenterata group live in water. The organisms of this group have cavity in their bodies. Hydra and sea anemone are the common example of coelenterate. Platyhelminthes The organisms of this group...

PLANTAE KINGDOM Introduction Plantae kingdom includes all sorts of plants belonging to multicellular eukaryotes. These plants are autotrophs and they use chlorophyll for the photosynthesis. Classification of Plantae Kingdom Based on distinct body structure, components, etc. plantae kingdom is further classified as: Thallophyta Bryophyta Pteridophyta Gymnosperms Angiosperms Let’s discuss each of them in brief: Thallophyta The plants of thallophyta do not have well-differentiated body design. The plants in thallophyta are known as algae and they are predominantly aquatic. Some of the significant examples of thallophyta are Spirogyra, Ulothrix, Cladophora, Chara, etc. Bryophyta The plants of amphibian group are categorized as bryophyta. Funaria Though not distinctly developed, but the plant body can be differentiated to form stem and leaf-like structures. The examples of bryophyta are moss (Funaria) and Marchantia. Pteridophyta Plants of pteridophyta have defined roots, stem, and leaves. ...

DIVERSITY IN LIVING ORGANISMS Introduction Biodiversity term is used to define the diversity of life forms. Biodiversity is a word more often used to refer to the variety of life forms found in a particular geographic region. Diversity of life forms of a geographic region provides stability in the respective region. Base of Classification Greek thinker Aristotle first classified animals based on their place of residence whether they lived on land, in water, or in the air. Later, all the living organisms are identified and categorized on the basis of their body design in form and function. The idea of evolution was first described by Charles Darwin in 1859 in his book namely – The Origin of Species.’ Charles Darwin first described this idea of evolution in 1859 in his book, ‘The Origin of Species.’ Hierarchy of Classification Groups Some biologists, namely Ernst Haeckel (1894), Robert Whittaker (1959), and Carl Woese (1977) have attempted to classify all living organisms into broad cate...

Animal Tissue ANIMAL TISSUE Introduction The tissue found in animals have comparatively some different properties than the plant tissue. Types of Animal Tissue Animal Tissues are divided as: Epithelial Tissue Connective Tissue Muscular Tissue Nervous Tissue Let’s discuss them in brief: Epithelial Tissue Epithelial tissues are the covering and protective tissues in the animal body. Epithelial tissue covers almost all organs and cavities within the body. Epithelial tissue also forms a barrier to keep different body systems separate. Epithelial tissue cells are closely packed and form a continuous layer. Connective Tissue Connective tissues are made up of the cells those are separated by non-living material, and known as an extracellular matrix. This matrix could be either liquid or rigid. Connective tissues are further divided as: Fibrous connective tissue Skeletal connective tissue and Fluid connective tissue Tendons are the example of fibrous connective tissue. Bone is an example of a ...

Plant Tissue TISSUES Introduction A group of cells that are similar in structure and work together to accomplish a particular function is known as tissue. Tissues are categorized as: Plant tissue & Animal tissue Plant Tissue Following are the major types of plant tissue: Meristematic Tissues Permanent Tissues Simple Permanent tissues Parenchyma Collenchyma Sclerenchyma Epidermis Complex Permanent Tissue Xylem Phloem Meristematic Tissue Meristematic tissue mainly consists of actively dividing cells, and helps in increasing the length and thickening the stems of the plant. Meristematic tissue, commonly, present in the primary growth regions of a plant, for example, in the tips of stems or roots. Depending on the region (where the meristematic tissues are found); meristematic tissues are classified as apical, lateral, and intercalary (see the image given below). Apical meristem (as shown in the above image) is present at the growing tips of stems and roots and helps in their growth. L...