Biology Test - 12

The correct order is: (iii), (i), (iv), (ii).

In lac operon

I gene - Repressor

z gene - β- galactosidase

y gene - Permease

a gene - Transacetylase.

The lac operon consists of : the regulatory I gene which codes for the repressor of the lac operon. structural gene z codes for beta-galactosidase (β-gal), which plays a role in the hydrolysis of lactose into galactose and glucose.

Simple squamous epithelium is a single layer of flat cells in contact with the basal lamina (one of the two layers of the basement membrane) of the epithelium. This type of epithelium is often permeable and occurs where small molecules need to pass quickly through membranes via filtration or diffusion.

Simple squamous epithelia are found lining the cavities of the body including the pericardial, pleural, and peritoneal cavities, or in areas where passive diffusion occurs, such as glomeruli in the kidney and alveoli in the respiratory tract.

Cell wall organelle acts as a pressure vessel.

The cell wall also acts as a pressure vessel, preventing over-expansion when water enters the cell by osmosis. The material in the cell wall varies. In plants and algae, the cell wall is made of long molecules of cellulose, pectin, and hemicellulose.

The correct match is: 1 - c, 2 - d, 3 - b, 4 - a.

• Psilotum -  Psilotum is a genus of fern-like vascular plants. It is one of two genera in the family Psilotaceae commonly known as whisk ferns, the other being Tmesipteris
• Marsilea -Marsilea is a genus of approximately 65 species of aquatic ferns of the family Marsileaceae. The name honours Italian naturalist Luigi Ferdinando Marsili (1656–1730).
• Selaginella - Selaginella is a pteridophyte. It is also called spikemoss or club moss. It is the largest and the only living genus of the family Selaginellaceae.
• Lycopsida - a subdivision of Tracheophyta coextensive with the class Lycopodineae comprising vascular plants (as the club mosses and related forms) with small leaves, sessile and adaxial sporangia, and no leaf gaps in the primary vascular cylinder — compare psilopsida , pteropsida , sphenopsida.

Translation proceeds in three phases:

Initiation: The ribosome assembles around the target mRNA. The first tRNA is attached at the start codon.

Elongation: The last tRNA validated by the small ribosomal subunit (accommodation) transfers the amino acid it carries to the large ribosomal subunit which binds it to the one of the precedingly admitted tRNA (transpeptidation). The ribosome then moves to the next mRNA codon to continue the process (translocation), creating an amino acid chain.

Termination: When a stop codon is reached, the ribosome releases the polypeptide. The ribosomal complex remains intact and moves on to the next mRNA to be translated.

Recent human population growth is attributed to:

• Agricultural revolution
• Industrial revolution
• Medical advances
• Altruistic behaviour

The last 100 years have seen a massive fourfold increase in the population, due to medical advances, lower mortality rates, and an increase in agricultural productivity made possible by the Green Revolution.

Filtration pressure in human kidneys is about \(15 \mathrm{~mm} \mathrm{Hg}\).

The filtration pressure that causes glomerular filtration is determined by three pressure:

1. Glomerular hydrostatic pressure
2. Colloid osmotic pressure of blood
3. Capsular hydrostatic pressure

The glomerular hydrostatic pressure(GHP) is the blood pressure in glomerular capillaries. It is due to the difference in the diameter of the afferent and efferent arteriole. It is \(60\) to \(76 \mathrm{~mm} \mathrm{~Hg}\).

The colloid osmotic pressure is the osmotic pressure produced in the blood of glomerular capillaries due to plasma proteins. It is \(30\) to \(32 \mathrm{~mm} \mathrm{~Hg}\).

The capsular hydrostatic pressure is the pressure produced by fluid which reaches into Bowman's capsule and resists filtration. It is about \(10\) to \(18 \mathrm{~mm} \mathrm{~Hg}\).

In leguminous plants leghemoglobin protects activity nitrogenase.

Nitrogenase enzyme produced by nitrogen fixing bacteria is a molybdo flavoprotein and is highly sensitive to oxygen. Hence, root nodules possess leghaemoglobin, which acts as a scavenger and binds free oxygen, thus, protecting the bacterial nitrogenase.

Biosphere reserves are included in the in-situ conservation.

In situ conservation: The conservation of genetic resources in natural populations of plant or animal species, such as forest genetic resources in natural populations of tree species.

It is the process of protecting an endangered plant or animal species in its natural habitat, either by protecting or cleaning up the habitat itself or by defending the species from predators. E.g., hot spots, National parks, Sanctuaries, Biosphere Reserves, and sacred groves.

Seeds in general, are the product of fertilization, a few flowering plants such as Asteraceae and grasses have evolved a special mechanism to produce seeds without fertilization is called Apomixis.It is a form of asexual reproduction that mimics sexual reproduction.It is of two types:

a) Adventive Embryony: It arises from the diploid saprophytic cell such as nucellus or integuments.

b) Recurrent Agamospermy: In this, diploid embryo sac is formed from megaspore mother cell which has the diploid egg which develops into the diploid embryo.

Example: Pear and Apple.