Comprehensive Biology Test

Secondary xylem is absent in non-woody plants and is present in trees and shrubs. Its cell walls are thickened by deposition of lignin, thereby, rendering mechanical support to such plants. The second  xylem consists of small tracheids and vessels and tyloses.

Transpiration is the major mechanism that derives the movement of water through a plant. It is described as the engine that pulls water up from the roots to leaves.

The chief function of the occipital lobe is controlling vision and visual processing. The occipital lobe helps us to see and identify different things, that we look at.

The main function of hypothalamus is homeostasis. It also controls all the autonomic regulatory activities of the body such as temperature and cardiovascular regulation.

Sickle-cell anemia is a disease caused by the replacement of a single amino acid to a single mutation in DNA.
 

Cerebellum posses more than 50% of the total neurons. It governs the co-ordination of movements.

It is the correct option. Evaporation of water from the leaves generates tension which transmits water up the trunk.

 An innate desire to change, which was a part of Lamarck's theory of evolution, is not a part of natural selection.

It is a genetic disease caused by a gene mutation. The gene controls the movement of salts and water into and out of the cells.The mutated form of the gene results in thick mucus to be secreted by the lungs, airways and pancreas, including many other symptoms. The mutated gene is recessive to the normal gene.

The occurrence of bacterial cells, has never been considered an exceptional mystery (though it too is explained by replicator theory).

All the male gametes will carry the dominant allele B. The female gametes will carry the recessive allele b. This means that the genotype of all the puppies will be Bb. Since the allele for black is dominant, all the puppies will be black.

This is the correct answer. The pure breeding male’s genome must be BB and the brown bitch’s genome must be bb. The allele for black fur is dominant over the brown allele. Therefore, all the offsprings will be black (Bb). The dog carries the X and Y chromosomes. The bitch carries two X chromosomes. At meiosis, only one of each chromosome pairs goes to the gametes.

Human sperm and egg are in the haploid states, i.e. they only have one copy of each chromosome, or 22 autosomes and one sex chromosome (either X or Y). Therefore, the most likely karyotype, of those listed, to be found in normal human sperm is 23, X. 23, Y is an equally likely karyotype in normal sperm.

Microsatellite instability results from aberrant mismatch repair and is characteristic of HNPCC.

This is the correct answer as sugars are transported in both the directions.

Yes, this is the single characteristic of those listed that determines that the cockroach is an insect.

Approximately 10% of patients with non-small cell lung cancer respond to gefitinib, which is predicted by EGF receptor gene mutation.

The 8;14 translocation activates the myc oncogene, which is a transcription factor.

A gene in a sperm cell, of a male is an active germ-line replicators having the possibility of unlimited further replication.

Double minute chromatin bodies are indicative of gene amplification, one of the mechanisms of oncogene activation.

According to the Punnett Square of this cross

This is the correct answer. Organisms are not replicators because their acquired characters are not passed on to future generations, only their genes are passed along.

It is correct the principle of clonal selection, and analog of natural selection, is implemented by the immune system.

Proto-oncogenes are normal cellular genes that, when activated by mutation, contribute towards the malignant phenotype. Gene amplification is a mechanism of proto-oncogene activation.

One expects a gain of function mutation in an oncogene, whereas nonsense mutation would result in loss of function.

This statement is incorrect. The tumor suppressor genes does not act dominantly in tumor cells.

The translocation (9;22), also called the Philadelphia chromosome, is a characteristic of chronic myelogenous leukemia.