Biology Test-1

The aerodynamic diameter of an irregular particle is signified as the diameter of the spherical particle with a density of 1000 kg/m3 and the same settling velocity as the irregular particle. It indicates the equivalent diameter of a sphere having the same volume as that of the Aerosol.

One can apply the aerodynamic diameter to particulate pollutants or to inhaled drugs to predict where in the respiratory tract such particles deposit. Pharmaceutical companies typically use aerodynamic diameter, not geometric diameter, to characterize particles in inhalable drugs.

Aerosols are defined as a combination of the liquid or solid particles suspended in a gaseous or liquid environment.

In the atmosphere, these particles are mainly located in the low layers of the atmosphere (< 1.5 km) since aerosol sources are located on the terrestrial surface.

The sedimentation constant of ribosome is generally 70S. Its breaks up into two subunits whose sedimentation constants are50S and 30S.

Prokaryotes have 70S ribosomes, each consisting of a small subunit (30S) and a large (50S) subunit. Their small subunit has a 16S RNA subunit (consisting of 1540 nucleotides) bound to 21 proteins. The large subunit is composed of a 5S RNA subunit (120 nucleotides), a 23S RNA subunit (2,900 nucleotides) and 31 proteins.

"The opening of the petals of dandelion flowers in bright light and closing in the dark at night is an example of phototropism" statement is not true.

The opening of the petals of dandelion flowers in bright light and closing in the dark at night is an example of photonastic movement. Opening in the morning light is called as positive photonastic movement, whereas the closing at night in response to light is called as negative photonasty.

Difference between tropic and nastic movements:

Tropisms are growth responses of plants that result in curvatures of plant organs toward or away from certain stimuli. Tropisms can be positive, in which case the plant will bend toward a stimulus or negative, in which case the plant will bend away from a stimulus. Important tropisms in plants include phototropism, gravitropism and thigmotropism.

Nastic movements are rapid movements of plant organs in response to a stimulus that results from alterations in cell volume in a specialized motor organ called a pulvinus. For example, handling of the touch-sensitive leaves of Mimosa pudica results in the folding of its leaflets within a few seconds and is an example of a thigmonastic movement.

The major source of Nitrous oxide and Sulphur Oxide pollution are power plants, Fossil fuel burning, Lightning, Industrial smoke, Chemical and Fertiliser Industries Volcanoes, Seas and Oceans, Decomposition of organic matter and vehicles.

\(\mathrm{N}_{2} \mathrm{O}_{3}, \mathrm{NO}_{2}\) and \(\mathrm{N}_{2} \mathrm{O}_{5}\) are acidic in nature, and when they react with water, they produce acids like \(\mathrm{HNO}_{3}\) (Nitric Acid) and \(\mathrm{HNO}_{2}\) (Nitrous Acid) which causes acid rain.

\(\mathrm{CO}\) and \(\mathrm{CO}_{2}\) react with rainwater to form weak Carbonic Acid. Thus generally rainwater is naturally slightly acidic.

A common biocontrol agent for the control of plant disease is trichoderma.

The natural method of pest and pathogen control involving use of viruses, bacteria and other insects (which are their natural predators and pests) is called biocontrol or biological control. For example, free living fungus Trichoderma exerts biocontrol over several plant pathogens for the control of plant diseases. Baculoviruses (mostly of genus Nucleo-polyhedrovirus) are also used as biocontrol agents but they are used for the control of insects and arthropods. Bacillus thuringiensis is a soil bacterium which is used as biopesticide. Glomus, species are the most common fungal partners of mycorrhiza residing in the roots of higher plants.

In vertebrates lacteals are found in ileum.

Ileum is the part of small intestine. Its mucosa is raised into numerous microscopic projections called the villi. The villi contain a minute blind ended lymph vessel lacteals. From the lacteals, the lipoprotein chylomicrons are carried into the blood stream directly via thoracic lymphatic duct.

The cytoplasm is a granular, crystallo-colloidal complex that forms the living protoplasm of a cell excluding its nucleus. It consists of proteins, nucleic acids, fats, carbohydrates, vitamins, minerals, waste metabolites, and all the organelles. It is the main area for various types of activities of cell-like respiration, nutrition, storage, etc.

The active form of entamoeba histolytica feeds upon erythrocytes, mucosa and sub mucosa of colon.

Entamoeba histolytica is a protozoan parasite responsible for a disease called amoebiasis. It occurs usually in the large intestine and causes internal inflammation. The life cycle of entamoeba histolytica does not require any intermediate host. Mature cysts (spherical, 1215 m in diameter) are passed in the feces of an infected human. Another human can get infected by ingesting them in fecally contaminated water, food or hands. If the cysts survive the acidic stomach, they transform back into trophozoites in the small intestine. Trophozoites migrate to the large intestine, where they live and multiply by binary fission. Both cysts and trophozoites are sometimes present in the feces. Cysts are usually found in firm stool, whereas trophozoites are found in loose stool. Only cysts can survive longer periods (up to many weeks outside the host) and infect other humans. If trophozoites are ingested, they are killed by the gastric acid of the stomach. Occasionally trophozoites might be transmitted during sexual intercourse. Damage is caused by the lysis of epithelial cells, due in part to the insertion of pore-forming proteins into the membrane of the cell. Neutrophils and non-activated macrophages may also be killed and ingested by the organism, limiting the ability of the immune system to deal with the disease entamoeba histolytica is also capable of phagocytosing red blood cells. They feed up on erythrocytes, mucosa and submucosa of colon.

Darwin proposed a theory of evolution called natural selection in the year 1859. According to it those populations which are a better fit (reproductively fit) in an environment will be selected by nature and will survive more.

Darwin conducted a sea voyage in a sailing ship called H.M.S Beagle as a part of his experiments on the theory of evolution.

Embryo of flowering plant is always Diploid (2n).

The plant life cycle alternates between haploid and diploid generations. Embryonic development is seen only in the diploid generation. The embryo, however, is produced by the fusion of gametes, which are formed only by the haploid generation.

The anterior part of the genital part contains the female gonopore, spermathecal pores and collateral glands. In males, the genital pouch lies at the hind end of abdomen. It is bound dorsally by the 9th and 10th terga and ventrally by the 9th sternum.

Intercalary meristemis found in petiole and internode.

The meristematic tissues that are present at the base of internodes of stem and petioles of leaves are known as Intercalary meristem. The function of these tissues is to promote the growth of the plants by elongating the nodes and internodes present at the leaves and stems. An alternative function of these tissues is in promoting the longitudinal growth of the leaves and stems especially in plants belonging to the grass family. These tissues are present on the base of leaf primordium in monocot plants. The elongation of petioles is a function of the intercalary meristem.

Secretion of gastric juice is stopped by enterogastrone.

An enterogastrone is any hormone secreted by the mucosa of the duodenum in the lower gastrointestinal tract in response to dietary lipids that inhibits the caudal (or forward, analward) motion of the contents of chyme.

Human insulin is produced from genetically engineered Escherichia coli. By using genetic engineering or recombinant DNA technology, insulin-producing genes from human beings have been transferred into Escherichia coli. bacteria, which produced insulin called 'humulin' for clinical use. This type of insulin was produced commercially by an American pharmaceutical firm Eli Lily on 5th July, 1983.

Pleurobrachia belongs to the phylum Ctenophora.

Ctenophores, commonly known as sea walnuts or comb jellies are exclusively marine, radially symmetrical, diploblastic organisms with tissue level of organisation. The body bears eight external rows of ciliated comb plates, which help in locomotion.

Digestion is both extracellular and intracellular.

Bioluminescence (the property of a living organism to emit light) is well-marked in ctenophores.

Sexes are not separate. Reproduction takes place only by sexual means. Fertilisation is external with indirect development.

Ctenoplana is also an example of Ctenophora.