Biology Part 1 Intermediate - Solved Guess Paper No. 1 MCQS

Biology Intermediate Part - 1 (11th Class)

Guess Paper No. 1

Total Marks: 17 (Objective Type) Time Allowed: 20 minutes

Q. 1 You have four choices for each objective type question as A, B, C and D. The choice which you think is correct; fill that circle in front of that question number. User marker or pen to fill the circles. Cutting or filling two or more circles will result in zero mark in that questions.

(i) Following structure is not concerned with lipid metabolism:

(A) SER (B) Glyoxisome

(ii) Nucleoli are not:

(A) Darkly stained (B) Membranous

(C) Variable in number (D) Factory of ribosome

(iii) Total animals, which have been discovered so far are:
(A) 0.5 million (B) 1.5 million
(C) 2.5 million (D) 3.5 million

(iv) Word vaccination was first used by:
(A) Edward Jenner (B) Louis Pasteur
(C) Robert Koch (D) C. Linnacus

(v) Which of the following is not an infectious disease?
(A) Polio (B) Typhoid
(C) Rabies (D) Cancer

(vi) Which is considered as small virus?
(A) Polio virus (B) Retrovirus
(C) Small pox (D) HIV

(vii) Feature not related to lytic cycle:
(A) Adsorption (B) Penetration
(C) Injection (D) Induction

(viii) Polio virus most commonly affects:
(A) Peripheral nerves (B) Spinal cord
(C) Brain (D) None of these

(ix) In small pox, areas which contain pus are called:
(A) Pustules (B) Scars
(C) Pocks (D) None of these

(x) Which of the following disease can develop autoimmunity?
(A) Influenza (B) Hepatitis
(C) Measles (D) Herpes simplex

(xi) Following statement is incorrect about HIV:
(A) Enveloped virus (B) Attached to WBC through receptor
(C) Transcriptase converts RNA into DNA (D) None of these

(xii) Hepatitis is caused by:
(A) Virus (B) Toxic agents
(C) Drugs (D) All of these

(xiii) HAV is:
(A) DNA enveloped (B) DNA non-enveloped
(C) RNA enveloped (D) RNA non-enveloped

(xiv) Type of hepatitis, which causes chronic liver disease is:
(A) Hepatitis A (B) Hepatitis B
(C) Hepatitis C (D) Hepatitis D

(xv) Antibiotics cannot kill:
(A) Streptococcus pneumonia (B) Staphylococcus
(C) Hepatitis virus (D) Tuberculosis bacteria

(xvi) Which one of the following is not related to cloning?
(A) Replacement of the nucleus of zygote, by another nucleus of the same organism
(B) Separation of an embryo to form more embryos
(C) The individual resulting have the similar biological make up
(D) Removal of the piece if DNA or gene from the cell and incorporating another gene or piece of DNA in its place

(xvii) Human beings can't digest cellulose because:
(A) Cellulose is hard to chew
(B) Cellulose can't be absorbed from small intestine after its digestion
(C) Cellulose can't be digested because of its composition
(D) Cellulose can't be digested because we lack enzyme to digest it

Answers:

(i) (D) (ii) (A) (iii) (C) (iv) (B)
(v) (D) (vi) (A) (vii) (D) (viii) (C)
(ix) (A) (x) (C) (xi) (D) (xii) (D)
(xiii) (D) (xiv) (C) (xv) (C) (xvi) (A)
(xvii) (D)

Biology Part 1 Intermediate - Solved Guess Paper No. 1 MCQS

Reviewed by SaQLaiN HaShMi on 9:45 AM Rating: 5

How to get a gene of interest?

SaQLaiN HaShMi 1:54 AM

GENE CLONING:

"The cloning in which identical copies of genes are produced is called gene cloning".

PCR (Polymerase Chain Reaction):

"The reaction which is used for production of lesser number of gene copies within test tube".

While, in case of formation of large gene copies recombinant DNA technology is used.

RECOMBINANT DNA TECHNOLOGY:

Recombinant DNA means a DNA with two different combination of genetic materials. (It is also called Chimeric DNA).

Method for Production of Recombinant DNA:

(i) Interest: Gene of interest (OR) selection, which is used to be cloned.

(ii) Cut out: Scissors enzymes (restriction endonuclease) to cut out the gene of interest.

(iii) Placement: Molecular carrier or VECTOR, on which gene of interest could be placed

(iv) Introduction: The gene of interest along with the vector is then introduced into an expression system, as a result of which a specific product is made.

Three ways to get the gene of interest:

(i) Isolation of gene from the chromosomes.

(ii) Synthesis of gene chemically.

(iii) Making of gene from mRNA.

Procedure:

(i) Isolation by restriction enzyme: The gene of interest can be isolated from the chromosomes by cutting restriction endonuclease is used to cut on the flanking sites of the gene.

(ii) Synthesis of small genes: In case of small genes they can also be synthesized in the laboratory.

(iii) Use of reverse transcriptase: Genes may be synthesized from mRNA by using the reverse transcriptase (an enzyme). This kind of DNA is called complementary DNA i.e, cDNA

How to get a gene of interest?

Reviewed by SaQLaiN HaShMi on 1:54 AM Rating: 5

Differentiate between Restriction endonuclease and ligase?

SaQLaiN HaShMi 2:04 AM

DEFINITIONS

Cloning:
A technique for developing large numbers of genetically identical cells or organisms is known as cloning.

Recombination:
Formation of a new association of DNA molecules or part of DNA molecules is termed as recombination.

Vector:
A plasmid that carries an inserted pieces of DNA into a host cell in recombinant DNA technology

(OR)

Any DNA molecule, such as plasmid, which serves to carry foreign DNA into host cells, where it may be replicated and expressed.

Gene:
An unit of inheritance is called gene.

Genome:
The total genetic constitution of an organism is known as genome.

Q No.2 Differentiate between restriction endonuclease and ligase?

Restriction Endonuclease (Scissor):
(i) It is the enzyme which can cut a DNA molecule within the strand.
(ii) It is also termed as "scissor".
(iii) "Restriction endonuclease" recognizes specific nucleotide sequence in DNA and then cut both strands in specific manner.

Ligase (Glue):
(i) The enzyme which has ability to seal up the DNA molecule.
(ii) Is is also termed as "glue".
(iii) "Enzyme that creates bonds between the ends of DNA molecules and form a large polynucleotide".

Differentiate between Restriction endonuclease and ligase?

Reviewed by SaQLaiN HaShMi on 2:04 AM Rating: 5

Biotechnology and Gene Therapy

SaQLaiN HaShMi 1:29 AM

BIOTECHNOLOGY:

"The molecular genetics which enables us to manipulate genetic materials for the welfare of mankind".

Desired varieties are formed by gene recombinations. These recombinant genes are made for the production of substance such as enzymes, antibiotics, and hormones needed for human use.

GENE THERAPY:

"The process by which faulty genes are replaced by normal genes is known as gene therapy".

Genotype and then Phenotype of organisms may be changed for important and good results by gene therapy. "Genetic engineering means manipulation of genes by man"

★ Gene Therapy in Bacteria

Many kinds of useful bacteria have been reproduced by genetic engineering:

(i) Clean up Pollutants: Some genetically engineered bacteria are used to clean up environmental pollutants.

(ii) Increase the Fertility of Soil: Certain bacteria have been engineered which increase the fertility of soil.

(iii) Kill Insects Pests: Bacteria are also used to kill insect pests.

★ Gene Therapy in Man

(i) Medical Applications: These include the production of hormones, vaccines, enzymes, antibodies, antibiotics and vitamins, and the gene therapy for some hereditary diseases.

(ii) Human insulin has been prepared by this method. It plays an important role in treating the diabetic patients.

Genetic engineering is also playing excellent role in industrial applications, environmental applications, agricultural applications and biological researches.

Biotechnology and Gene Therapy

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Continuous Variation, Molecular Basis Of Allelic Variation

SaQLaiN HaShMi 6:29 AM

CONTINUOUS VARIATION A character showing continuous variation has an unbroken range of phenotypes in a population (see Figure 1-10b). Measurable characters such as height, weight, and skin or hair color are good examples of such variation. Intermediate phenotypes are

generally more common than extreme phenotypes. In some cases, all the variation is environmental and has no genetic basis, as in the case of the different languages spoken by different human groups. In other cases, such as that of the various shades of human eye color, the differences are caused by allelic variation in one or many genes. For most continuously variable characters, both genetic and environmental variation contribute to differences in phenotype. In continuous variation, there is no one-to-one correspondence of genotype and phenotype. For this reason, little is known about the types of genes underlying continuous variation, and only recently have techniques become available for identifying and characterizing them.

Continuous variation is encountered more commonly than discontinuous variation in everyday life. We can all identify examples of continuous variation, such as variation in size or shape, in plant or animal populations that we have observed—many examples exist in human populations. One area of genetics in which continuous variation is important is in plant and animal breeding. Many of the characters that are under selection in breeding programs, such as seed weight or milk production, arise from many gene differences interacting with environmental variation, and the phenotypes show continuous variation in populations. We shall return to the specialized techniques for analyzing continuous variation in Chapter 20, but for the greater part of the book, we shall be dealing with the genes underlying discontinuous variation.

Molecular basis of allelic variation

Consider the difference between the pigmented and the albino phenotypes in humans. The dark pigment

melanin has a complex structure that is the end product of a biochemical synthetic pathway. Each step in the pathway is a conversion of one molecule into another, with the progressive formation of melanin in a step-by-step manner. Each step is catalyzed by a separate enzyme protein encoded by a specific gene. Most cases of albinism result from changes in one of these enzymes—tyrosinase. The enzyme tyrosinase catalyzes the last step of the pathway, the conversion of tyrosine into melanin.

To perform this task, tyrosinase binds to its substrate, a molecule of tyrosine, and facilitates the molecular changes necessary to produce the pigment melanin. There is a specific “lock-and-key” fit between tyrosine and the active site of the enzyme. The active site is a pocket formed by several crucial amino acids in the polypeptide. If the DNA of the tyrosinase-encoding gene changes in such a way that one of these crucial amino acids is replaced by another amino acid or is lost, then there are several possible consequences. First, the enzyme might still be able to perform its functions but in a less efficient manner. Such a change may have only a small effect at the phenotypic level, so small as to be difficult to observe, but it might lead to a reduction in the amount of melanin formed and, consequently, a lighter skin coloration. Note that the protein is still present more or less intact, but its ability to convert tyrosine into melanin has been compromised. Second, the enzyme might be incapable of any function, in which case the mutational event in the DNA of the gene would have produced an albinism allele, referred to earlier as an a allele. Hence a person of genotype a/a is an albino.

The genotype A/a is interesting. It results in normal pigmentation because transcription of one copy of the wild type allele (A) can provide enough tyrosinase for synthesis of normal amounts of melanin. Genes are termed haplosufficient if roughly normal function is obtained when there is only a single copy of the normal gene. Wild-type alleles commonly appear to be haplosufficient, in part because small reductions in function are not vital to the organism. Alleles that fail to code for a functional protein are called null (“nothing”) alleles and are generally not expressed in combination with func-

tional alleles (in individuals of genotype A/a). The molecular basis of albinism is represented in Figure 1-13. Third, more rarely, the altered protein may perform its function more efficiently and thus be the basis for future evolution by natural selection.

The mutational site in the DNA can be of a number of types. The simplest and most common type is

nucleotide-pair substitution, which can lead to amino acid substitution or to premature stop codons. Small deletions and duplications also are common. Even a single base deletion or insertion produces widespread damage at the protein level; because mRNA is read from one end “in frame” in groups of three, a loss or gain of one nucleotide pair shifts the reading frame, and all the amino acids translationally downstream will be incorrect. Such mutations are called frameshift mutations.

At the protein level, mutation changes the amino acid composition of the protein. The most important

outcomes are change in protein shape and size. Such change in shape or size can result in an absence of biological function (which would be the basis of a null allele) or reduced function. More rarely, mutation can lead to new function of the protein product.

Continuous Variation, Molecular Basis Of Allelic Variation

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Genetic Variation, Types of Variation

SaQLaiN HaShMi 2:02 AM

1.2 Genetic variation

If all members of a species have the same set of genes, how can there be genetic variation? As indicated earlier, the answer is that genes come in different forms called alleles. In a population, for any given gene there can be from one to many different alleles; however, because most organisms carry only one or two chromosome sets per cell, any individual organism can carry only one or two alleles per gene. The alleles of one gene will always be found in the same position along the chromosome. Allelic variation is the basis for hereditary variation.

Types of variation

Because a great deal of genetics concerns the analysis of variants, it is important to understand the types of variation found in populations. A useful classification is into discontinuous and continuous variation (Figure 1-10). Allelic variation contributes to both.

DISCONTINUOUS VARIATION Most of the research in genetics in the past century has been on discontinuous variation because it is a simpler type of variation, and it is easier to analyze. In discontinuous variation, a character is found in a population in two or more distinct and separate forms called phenotypes. “Blue eyes” and “brown eyes” are phenotypes, as is “blood type A” or “blood type O.” Such alternative phenotypes are often found to be encoded by the alleles of one gene. A good example is albinism in humans, which concerns phenotypes of the character of skin pigmentation. In most people, the cells of the skin can make a dark-brown or black pigment called melanin, the substance that gives our skin its color ranging from tan color in people of European ancestry to brown or black in those of tropical and sub-tropical ancestry. Although always rare, albinos, who completely lack pigment in their skin and hair, are found in all races (Figure 1-11). The difference between pigmented and unpigmented skin is caused by different alleles of a gene that encodes an enzyme involved in melanin synthesis.

The alleles of a gene are conventionally designated by letters. The allele that codes for the normal form of the enzyme involved in making melanin is called A, and the allele that codes for an inactive form of that enzyme (resulting in albinism) is designated a, to show that they

are related. The allelic constitution of an organism is its genotype, which is the hereditary underpinning of the phenotype. Because humans have two sets of chromosomes in each cell, genotypes can be either A/A, A/a, or a/a (the slash shows that the two alleles are a pair). The phenotype of A/A is pigmented, that of a/a is albino, and that of A/a is pigmented. The ability to make pigment is expressed over inability (A is said to be dominant, as we shall see in Chapter 2).

Although allelic differences cause phenotypic differences such as pigmented and albino coloration, this does not mean that only one gene affects skin color. It is known that there are several, although the identity and number of these genes are currently unknown. However, the difference between pigmented, of whatever shade, and albinism is caused by the difference in the alleles of one gene—the gene that determines the ability to make melanin; the allelic composition of other genes is irrelevant.

In some cases of discontinuous variation, there is a predictable one-to-one relation between genotype and phenotype under most conditions. In other words, the two phenotypes (and their underlying genotypes) can almost always be distinguished. In the albinism example, the A allele always allows some pigment formation, whereas the a allele always results in albinism when present in two copies. For this reason, discontinuous variation has been successfully used by geneticists to identify the underlying alleles and their role in cellular functions.

Geneticists distinguish two categories of discontinuous variation. In a natural population, the existence of two or more common discontinuous variants is called polymorphism (Greek; many forms). The various forms are called morphs. It is often found that different morphs are determined by different alleles of a single gene. Why do populations show genetic polymorphism? Special types of natural selection can explain a few cases, but, in other cases, the morphs seem to be selectively neutral.

Rare, exceptional discontinuous variants are called mutants, whereas the more common “normal” phenotype is called the wild type. Figure 1-12 shows an example of a mutant phenotype. Again, in many cases, the wild-type and mutant phenotypes are determined by different alleles of one gene. Both mutants and polymorphisms originally arise from rare changes in DNA (mutations), but somehow the mutant alleles of a polymorphism become common. These rare changes in DNA may be nucleotide-pair substitutions or small deletions or duplications. Such mutations change the amino acid composition of the protein. In the case of albinism, for example, the DNA of a gene that encodes an enzyme involved in melanin synthesis is changed, such that a crucial amino acid is replaced by another amino acid or lost, yielding a nonfunctioning enzyme. Mutants (such as those that produce albinism) can occur spontaneously in nature, or they can be produced by treatment with mutagenic chemicals or radiation.

Geneticists regularly induce mutations artificially to carry out genetic analysis because mutations that affect some specific biological function under study identify the various genes that interact in that function.