Biology: Topic-wise Test- 7 - NEET MCQ

Option (b) is the correct answer because when restriction enzymes cut the strand of DNA a little away from the centre of the palindrome sites, but between the same two bases on the opposite strands, then single stranded portions are left at the ends. These overhanging stretches on each strand are called sticky ends.

• Microbes are not used in the production of antiviral drugs and the production of inorganic fertilizers.
• Although, microbes are used in converting milk into curd, antibiotic production, sewage treatment, bread and cheese industry etc.

Hence, the correct option is C.
NCERT Reference: Topic- MICROBES IN SEWAGE TREATMENT” and  MICROBES IN INDUSTRIAL PRODUCTS” of chapter "Microbes in Human Welfare" of NCERT.  

• The external genitalia are accessory structures of female reproductive system that are external to vagina they are also referred to as vulva or pudendum.
• The external genitalia includes the labia majora, mons pubis, labia minora, clitoris and glands within vestibules.
  

Hence, the correct option is B.

NCERT Reference: Topic "THE FEMALE REPRODUCTIVE SYSTEM” of chapter " Human Reproduction of NCERT

• Monohybrid ratio is the ratio of different phenotypic traits obtained on hybridizing a single pair of traits. It is 3:1.
• When tall pea plant is crossed with dwarf, the offspring obtained are in 3/4 tall and 1/4 dwarf.

Fig: Monohybrid cross

Hence, the correct option is B
NCERT Reference: Topic: " INHERITANCE OF ONE GENE” of chapter "Principles of Inheritance and Variation" of NCERT

• Clostridium butylicum is used to produce butyric acid.
• Butyric acid is an important industrial chemical used to process food items.

Hence, the correct option is A.
NCERT Reference: Topic-  Chemicals, Enzymes and other Bioactive Molecules” of chapter "Microbes in Human Welfare" of NCERT.  

The primary sex organ of human males is the Testis.
Testis:

Male Reproductive System:

Fig: Image of primary sex organ in male i.e. Testes

• The testis is a major male reproductive organ that produces sperm and hormones, primarily testosterone.
• Testes are located in the scrotum, a pouch-like structure that hangs outside the body, which helps maintain an optimal temperature for sperm production.
• Testes consist of numerous seminiferous tubules where sperm cells are produced through a process called spermatogenesis.
• The hormone testosterone produced by the testes is responsible for the development of secondary sexual characteristics such as facial hair, deepening of the voice, and muscle growth in males.
• Testes also produce inhibin, a hormone that regulates sperm production by inhibiting the secretion of follicle-stimulating hormone (FSH).

NCERT Reference: Topic “THE MALE REPRODUCTIVE SYSTEM” of chapter: Human Reproduction

Maize grain is monocotyledonous, having a single cotyledon. This cotyledon is also called scutellum.

Filiform apparatus is finger-like projection attached with egg apparatus. This apparatus guide the pollen tube carrying male gametes for facilitating Syngamy.

About 60% of angiosperms, pollen grains are shed at two celled stage. The larger cell is called vegetative cell and the smaller one is called generative cell. Each generative cell produces two male gametes.

The flower in which pollen grain is transferred from anther to stigma of anther flower by insects are colorful to attract insects and contain nectar.

• Biological oxygen demand is the amount of oxygen required to completely decompose the organic waste present in one litre of water by bacteria.
• A high value of BOD shows that water is highly polluted.

Hence, the correct option is A.
NCERT Reference: Topic- MICROBES IN SEWAGE TREATMENT” of chapter "Microbes in Human Welfare" of NCERT.  

• Transfer of male gametes (sperm) into the female genital tract occurs during sexual intercourse that may lead to the fertilisation of the ovum for pregnancy.
• Sexual intercourse is called coition or coitus.

Hence, the correct option is B.
NCERT Reference: topic “FERTILISATION AND IMPLANTATION” of chapter: Human Reproduction.

The correct sequences of process of recombinant DNA technology are Isolation of DNA, fragmentation of DNA by restriction endonuclease, isolation of desired DNA fragment, ligation of DNA fragment into vector, transferring of into host and culturing in host cell to get desired product.

• Mendel studied the common garden pea plant, Pisum sativum because it was easy to cultivate and had a relatively short life cycle of 3 months. The plant exhibited discontinuous characteristics such as flower colour and pea texture.
• Owing to its anatomy, it was easy to control the self-pollination of the plant and cross-fertilization between desired parents could be accomplished artificially.
• The presence of pure breeding varieties and easily visible contrasting characters and presence of F₁ fertile hybrids were the additional advantageous characters for which Mendel choose garden pea as experimental material. 

Hence, the correct option is C

NCERT Reference: Topic “MENDEL’S LAWS OF INHERITANCE” of chapter "Principles of Inheritance and Variation" of NCERT

In monohybrid and dihybrid cross F₂ generation is obtained by selfing of F₁ hybrids as male and female.

Fig: Monohybrid cross showing F₁ and F₂ generation

Hence, the correct option is B

NCERT Reference: Topic " INHERITANCE OF ONE GENE " of chapter Principles of Inheritance and Variation" of NCERT

Protein can be digested by using enzyme protease to obtain DNA. In chromosome DNA is wrapped on histone protein.

DNA molecules are replicated in both meiosis and mitosis.  DNA unwinds and unzips along its base pair chemical bonds.  Free nucleotides then connect to the exposed base pairs on both strands resulting in the formation of the missing side of each new DNA.

• Each testis contains about 250 compartments called testicular lobules.
• Each testicular lobule contains one to three highly coiled seminiferous tubules that produce sperms.

Fig: Image showing testicular lobules consists of seminiferous tubules. 

Hence, the correct option is D.

NCERT Reference: topic “THE MALE REPRODUCTIVE SYSTEM” of chapter: Human Reproduction.

• Syngamy is the process of fusion of a haploid male(n) and a haploid female(n) gamete.
• On fusion, the zygote or the egg formed is diploid(2n).
• Often this process is also known as fertilization.

Option (d) is the correct answer. Cloning vectors are the carriers of the desired gene in the host cell. The features desirable in a cloning vector are :-

• Presence of origin of replication
• Presence of marker genes
• Presence of very few, preferably single recognition site for the commonly used restriction enzymes

Ovule/s are located inside the ovary. The point of attachment of the ovule to the ovary is called the funicle. Funicle extends to hilum as stalk.

DNA finger printing is highly reliable method of identification of individual involved in crimes. DNA a fingerprinting is a sure method in solving paternity and maternity disputes.DNA fingerprinting cannot be used to cure HIV infection.

• Due to the development of various methods of genetic engineering, in the last decade or so, scientists have introduced Bacillus thuringiensis toxin genes into the plants. Such plants are resistant to attack by insect pests.
• These are available in sachets as dried spores which are mixed with water and sprayed onto vulnerable plants such as brassicas and fruit trees, where these are eaten by the insect larvae. In the gut of the larvae, the toxin is released and the larvae get killed. The bacterial disease will kill the caterpillars, but leave other insects unharmed.
• Bt-cotton is one such example, which is being cultivated in some states of our country.

Hence, the correct option is A.
NCERT Reference: Topic- MICROBES AS BIOCONTROL AGENTS” of chapter "Microbes in Human Welfare" of NCERT.  

The mature anther consists of four microsporangia which contain four layers. The inner most layer is called tapetum that provide nutrient to growing microspores and tissues inside it are called microspore mother cell that produce pollen grain.

• It is made almost exclusively in the placenta.
• hCG hormone levels found in the mother's blood and urine, rise a lot during the first trimester. 
• hCG Maintains the corpus luteum throughout the early stages of pregnancy. It is used to detect pregnancy.

Hence, the correct option is B.

NCERT Reference: topic “PREGNANCY AND EMBRYONIC DEVELOPMENT” of chapter: Human Reproduction.

• Interstitial cells or Leydig cells are found adjacent to seminiferous tubules in the testicles.
• They produce testosterone in the presence of luteinizing hormones.
• Leydig cells are polyhedral in shape and have a large prominent nucleus, an eosinophilic cytoplasm and numerous lipid-filled vesicles.
• Leydig cells synthesise and secrete testicular hormones called androgens.

Hence, the correct option is B.
NCERT Reference: topic “THE MALE REPRODUCTIVE SYSTEM” of chapter: Human Reproduction .

• Some of the aerobic nitrogen-fixing bacteria are Azotobacter and Beijerinckia.
• Some of the anaerobic nitrogen-fixing bacteria are Clostridium, Rhodospirillum and Rhodopseudomonas.
• Soil is enriched through exudation and the formation of nitrates after their death and decay.

Hence, the correct option is A.
NCERT Reference: Topic- MICROBES AS BIOFERTILISERS” of chapter "Microbes in Human Welfare" of NCERT.  

• The type of gas produced depends upon the microbes and the organic substrates they utilise.
• Example: In the fermentation of dough, cheese making and production of beverages, the main gas produced is CO₂.

Hence, the correct option is C.
NCERT Reference: Topic- MICROBES IN PRODUCTION OF BIOGAS” of chapter "Microbes in Human Welfare" of NCERT.  

Both the statements are correct but the given reason is not the correct explanation. Polymerase chain reaction is used in DNA amplification.

Ampicillin resistance gene is a selectable marker that helps to check transformation by selection of transformants.

• Females have the genetic composition XX, while males have the genetic makeup XY.
• The female ovum has an X chromosome, whereas male sperm might have either an X or a Y chromosome.
• When X chromosome-carrying sperm fertilises an egg with an X chromosome, the zygote grows into a female.

Hence, the correct option is B.

NCERT Reference: Topic- SEX DETERMINATION” of chapter  "Principles of Inheritance and Variation" Of NCERT.