Biology Test - 22

Sunken stomata are not directly visible to the leaf surface. They are found beneath the epidermis and beneath the leaves of plants. Xerophytes have sunken stomata to prevent water loss from the plant. They are often enclosed and partially covered by cuticles and are sunken within the leaf rather than on the surface. Therefore statement (A) is not true.

The stem of the aquatic plants is flexible because it helps the leaves to float. They bend with the flow of water so the plants do not get damaged by strong current. Therefore statement (B) is true.

Heterophylly is one of the methods of plasticity in which plant follow several pathways in response to the external environment. Plants like cotton, coriander, larkspur and buttercup have leaves in juvenile phase which are entirely different from the mature phase. Also, differ in either the plant is aquatic or terrestrial.  Therefore statement (C) is true.

Generally, hydrophytes have poorly developed root systems. This is because their other adaptations allow them to gain all the nutrients they need from their aquatic environment. Therefore statement (D) is true.

No waxy cuticle, or a very thin one, can be found on the leaves of hydrophytes . Due to the excess of water available to them, there is no need for a waxy cuticle, since reducing water loss is not a factor these plants have needed to adapt to. Therefore statement (E) is not true.

There can be 36 ATP molecule during aerobic respiration of one molecule of glucose.

The NADH₂ molecule produced during glycolysis cannot enter directly into mitochondria. This entry of glycolytic energy inside mitochondria is performed either by using the glycerol-3-phosphate shuttle or by Malate- asparate shuttle. These shuttles do not occur in prokaryotes.

Glycerol 3 phosphate shuttle: It explains that there is a loss of 1 ATP for each cytosolic NADH⁺ H⁺. Net ATP produced in respiration is 36 instead of 38 ATP. It occurs in flight muscles cells and brains.

Malate-aspartate shuttle: It occurs in heart, kidney and other organs. 38 ATP is produced as a net in aerobic respiration.

Therefore, total net gain ATP = 36 or 38 depending upon the type of shuttle system used in aerobic respiration.

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.

Bacteria are the sole members of the Kingdom Monera. They are the most abundant micro-organisms.

On the basis of origin, bacteria can be divided into two types - Archaebacteria & Eubacteria.

Archaebacteria:

These bacteria are special since they live in some of the harshest habitats such as extreme salty areas (halophiles), hot springs (thermoacidophiles) and marshy areas (methanogens).

Archaebacteria differ from other bacteria in having a different cell wall structure and this feature is responsible for their survival in extreme conditions.

For example - Methanogens are present in the gut of several ruminant animals such as cows and buffaloes and they are responsible for the production of methane (biogas) from the dung of these animals.

Diffusion is a phenomenon in which molecules move from an area of high concentration to an area of low concentration. An example of this process is a gaseous exchange of oxygen and carbon dioxide between alveolar air and capillaries. The blood in the capillaries surrounding the alveoli has a lower concentration of oxygen than the oxygen in the inhaled air. Therefore, O_2​ diffused from the alveoli to the capillaries. The blood in the surrounding capillaries has a higher concentration of carbon dioxide than the inspired air. So, CO₂​ diffuses from the capillaries into the alveoli where it is then exhaled.

The male reproductive systemincludes a pair oftestesalong with accessory ducts, glands, and the external genitalia. Each testis has about 250 compartments calledtesticular lobules.Each lobule contains one to three highly coiledseminiferous tubulesin which sperms are produced. Each seminiferous tubule is lined on its inside by two types of cells calledmale germ cells (spermatogonia) and Sertoli cells.The male germ cells undergo meiotic divisions finally leading to sperm formation, while Sertoli cells provide nutrition to the germ cells.The regions outside the seminiferous tubules called interstitial spaces contain small blood vessels andinterstitial cellsorLeydig cells.

Leydig cells synthesise and secrete testicular hormones called androgens.

Vas Deferensis the name of the muscular tube that transports sperm from the testes to the penis.

There are two of these ducts, which are tubes surrounded by smooth muscle. They connect the left and right epididymis to the ejaculatory ducts in order to move sperm.

Biomes are defined by: Plant structures, leaf types, climate, plant spacing.

Biomes. A biome is an area classified according to the species that live in that location. Temperature range, soil type, and the amount of light and water are unique to a particular place and form the niches for specific species allowing scientists to define the biome.

The given figure is of a false fruit. False fruit develops from other floral parts and thalamus alongwiththe development of ovary wall.

The secretory material is discharged by the golgi vesicles, from the surface of cell membrane byReverse pinocytosis.

The secretory pathway refers to the endoplasmic reticulum, Golgi apparatus and the vesicles that travel in between them as well as the cell membrane and lysosomes.

Reverse pinocytosis is opposite of pinocytosis or vomiting of cells. The membrane covering of a vesicle fuses with the plasma membrane, a channel opens between the lumen of the vesicle and the exterior of the cell, and the exportable material passes out.