31. Bacteria protect themselves from viruses by fragmenting viral DNA?
[A] Ligase
[B] Endonuclease
[C] Exonuclease
[D] Gyrase
Show Answer
Correct Answer: C [Exonuclease]
Notes:
Bacteria protect themselves from viruses by fragmenting viral DNA with Exonuclease. Enzymes that work by cleaving one nucleotide at a time from the end (Exo) of the polynucleotide chain are called exonucleases.
32. Typhoid fever is caused by ____:
[A] Virus
[B] Bacteria
[C] Fungus
[D] Allergy
Show Answer
Correct Answer: B [Bacteria]
Notes:
Typhoid fever, also known as typhoid, is a common water borne worldwide bacterial disease, transmitted by the ingestion of food or water contaminated with the feces of an infected person, which contain the bacterium Salmonella Typhi.
33. A cross between homozygous recessive and heterozygous plant is
____:
[A] Back cross
[B] Test cross
[C] Monohybrid cross
[D] Dihybrid cross
Show Answer
Correct Answer: B [Test cross]
Notes:
A cross between a homozygous plant with recessive traits and a heterozygous plant is known as a test cross. A test cross is a valuable tool in predicting the genotype of the organism in question. In its simplest form, a test cross is an experimental cross of an individual organism of dominant phenotype but unknown genotype and an organism with a homozygous recessive genotype (and phenotype). Test cross is done to determine the genotype of an F2 generation plant, showing dominant characteristics. In the test cross, an F2 plant that shows the dominant trait is crossed with the homozygous recessive.
34. What is Blood?
[A] Muscular tissue
[B] Epithelial tissue
[C] Reproductive tissue
[D] Connective tissue
Show Answer
Correct Answer: D [Connective tissue]
Notes:
Blood is considered a connective tissue for two basic reasons:
(i) embryologically, it has the same origin (mesodermal) as do the other connective tissue types and
(ii) blood connects the body systems together bringing the needed oxygen, nutrients, hormones and other signaling molecules, and removing the wastes.
35. The biological process in which both aerobes and anaerobes degrade organic matter is ____:
[A] Digesting
[B] Composting
[C] Manuring
[D] Nutrifying
Show Answer
Correct Answer: B [Composting]
Notes:
Composting is the depomposition of plant remains and other once-living materials to make an earthy, dark, crumbly substance that is excellent for enriching soil. It is the chief way to recycle wastes.
36. Consider the following statements about how plants absorb nitrogen:
- Plants absorb nitrogen in the form of inorganic nitrates or nitrites.
- Plants take in nitrogen in the form of organic compounds.
- Nitrogen is directly taken up by the plants from the atmosphere.
Which of the above statements is / are correct?
[A] Only 1 and 2
[B] Only 1 and 3
[C] Only 2 and 3
[D] All of these
Show Answer
Correct Answer: A [Only 1 and 2]
Notes:
Plants obtain nitrogen through their roots. In the soil, nitrifying bacteria change ammonia into nitrite (NO2 –) and then into nitrate (NO3 –), this process is known as nitrification. Furthermore, plants also absorb nitrogen in an organic form. Several organic compounds (compounds containing carbon) constitute the organic fraction of nitrogen in the soil. The organic matter in the soil exists as decomposing plant and animal residues, relatively stable decomposition-resistant compounds, and humus. The abundance of various forms of nitrogen can be altered by plant roots through the change in pH and secretion of organic compounds or oxygen.
37. The pigment that gives human skin, hair and eyes their colour is called ____:
[A] Quinacridone
[B] Alizarin
[C] Melanin
[D] Phthalocyanine
Show Answer
Correct Answer: C [Melanin ]
Notes:
The pigment that gives human skin, hair, and eyes their color. Dark-skinned people have more melanin in their skin than light-skinned people have. Melanin is produced by cells called melanocytes. Everyone has the same number of melanocytes, but some people make more melanin than others.
38. In which of the following multiple epidermis is found?
[A] Boerhaavia
[B] Nerium
[C] Amaranthus
[D] Helianthus
Show Answer
Correct Answer: B [Nerium]
Notes:
It is assumed that protodermal cells divide periclinally in certain cases to form multiseriate or multiple epidermis. The multiple epidermis is found in some organs like roots of orchids (Vanda), leaves of Ficus, Nerium, Piperomia, etc. In Nerium, it is found on both surfaces.
39. A molecule in plants comparable to haemoglobin in animals is ____:
[A] Carotene
[B] Chlorophyll
[C] Cellulose
[D] Cytochrome
Show Answer
Correct Answer: B [Chlorophyll]
Notes:
Haemoglobin is the iron-containing oxygen transporting metalloprotein in the red blood cells of all vertebrates. Similarly, Cytochromes are, in general, membrane-bound haemo-proteins containing heme groups and are primarily responsible for the generation of ATP via electron transport.
40. Which of the following bacterium causes crown gall disease in plants?
[A] Agrobacterium tumefaciens
[B] Pseudomonas fluorescens
[C] Bacillus thurigiensis
[D] None of the above
Show Answer
Correct Answer: A [Agrobacterium tumefaciens]
Notes:
Crown gall is a disease caused by the bacterium Agrobacterium tumefaciens (synonym Rhizobium radiobacter), which enters the plant through wounds in roots or stems and stimulates the plant tissues to grow in a disorganized way, producing swollen galls. As the disease progresses, plants lose vigour and may eventually die. In science of Biotechnology, it is considered as natural engineer.