Biology Test - 33

Change in the base sequence within a gene is calledMutation.

A mutation is a change in a DNA sequence.Mutations can result from DNA copying mistakes made during cell division, exposure to ionizing radiation, exposure to chemicals called mutagens, or infection by viruses.

In the Hershey and Chase experiments, they used bacteriophages (viruses that infect bacteria) and grew one batch in the presence of radioactive phosphorus (P32) and another batch in the presence of radioactive sulfur (S35).
Phosphorus is a component of DNA but not of protein. Therefore, any virus particles grown in the presence of radioactive phosphorus would have radioactive DNA, which is statement (A).
Sulfur is found in proteins (in the amino acids methionine and cysteine) but not in DNA. Therefore, any virus particles grown in the presence of radioactive sulfur would have radioactive protein, which is statement (B).
Statements (C), (D), and (E) are incorrect because they do not align with the components of DNA and proteins, and where sulfur and phosphorus are found in these molecules.
The Hershey and Chase experiments were key in establishing that DNA, not protein, is the genetic material. When these radioactive viruses infected bacteria, they found that the radioactive DNA (from phosphorus) was transferred to the bacteria, not the radioactive protein (from sulfur).

The largest gene in humans is Dystrophin.

The dystrophin gene (DMD) is the largest gene in t human genome, mapping on the Xp21 chromosome locus. It spans 2.2Mb and accounts for approximately 0,1% of the entire human genome. Mutations in this gene cause Duchenne and Becker Muscular Dystrophy, X-linked Dilated Cardiomyopathy, and other milder muscle phenotypes.

After vascular injury, platelets encounter extracellular matrix constituents such as collagen and adhesive glycoprotein. On contact with adhesion, secretion and aggregation proteins platelets undergo.

Platelet adhesion is an essential function in response to vascular injury and is generally viewed as the first step during which single platelets bind through specific membrane receptors to cellular and extracellular matrix constituents of the vessel wall and tissues. This response initiates thrombus formation that arrests hemorrhage and permits wound healing.

Proteins are liable to saturate, respond to inhibitors, under hormonal regulation and highly selective, thus, are responsible for facilitated diffusion.

Peroxisomes are involved in photorespiration. Photorespiration is a wasteful process that occurs when RuBP binds to oxygen in presence of RuBisCO. There is no synthesis of sugars rather there is utilisation of ATP. Photorespiration occurs in three organelles - chloroplast, peroxisomes, and mitochondria.

Calvin cycle, CAM pathway, and C₄ cycle occur in chloroplasts.

Coelenterata is a phylum that consists of animals that have stinging capsules or cnidoblasts on tentacles or the body which is used for anchorage, defence and capture of prey. So, they are also called cnidarians.

Zygote is formed inside the female gametophyte.

A zygote forms when a sperm penetrates the outer surface of an egg. This happens in the fallopian tube. While the zygote stage is very brief, lasting only the early days of conception, it is important. The single-celled zygote contains all of the genetic information required to form a fetus.

Embryo sac contains 1 egg.

The embryo sac or which is also called as the female gametophyte is an oval structure which is situated in the ovule of flowering plants. - There is only one egg in an embryo sac. - Number of embryo sacs present in an ovule is one. - Numbe of ovules in an ovary varies from plant to plant.

Tropical Rainforests has the maximum bio-diversity.

Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as lowland equatorial evergreen rainforest.