Biology Test - 42

Pneumatic bones are found inClass Aves.

Introduction to the class Aves:

All the birds are included in the class Aves.Their body is boat-shaped and divided into head, neck, trunk and tail.Their body is covered with soft feathers called ''plumage''Birds are warm-blooded animals or homeothermic i.e. their temperature remains constant with respect to the outside temperature.

Mammals have a bony endoskeleton, the skull is dicondylic. Vertebrae are acoelous or amphibian type i.e. centrum is flat at both sides. Cartilagenous pads are found at the edges of the centrum, which are called epiphysis.

Reptiles have a chevron bone found in the caudal vertebrae.

Osteichthyes: It is a class of fishes that has bones in their endoskeleton so they are called Bony fishes.

Flying fish is an example of a true fish. True fishes fall under the phylum- Chordata, subphylum- Vertebrata and class- Pisces in the Animal Kingdom. These fishes are characterized by the presence of a notochord, paired gills, a tubular nerve cord, post-anal tail, endoskeleton, and a segmented body.

Silverfish is a wingless insect that falls under the phylum- Arthropoda.Cuttlefish is a marine animal which falls under the phylum- Mollusca.Jellyfish are also marine animals that come under the phylum- Cnidaria.

A person is injected with globulin against hepatitis. This is artificially acquired active immunity.

Acquired immunity is characterized by memory and pathogen-specific.In the case of active immunity, antibodies are produced in the host body when a host is exposed to antigens, which may be in the form of living or dead microbes. Active immunity is a fully effective response but is slow and takes time. Injecting microbes deliberately during immunization or infectious organisms gaining access into the body during natural infection can induce active immunity.

Option A : Over-exploitation, habitat loss and fragmentation.
Each of the factors listed in this option can contribute to biodiversity loss:
Over-exploitation : When species are over-hunted, over-fished, or harvested at rates faster than their natural ability to recover, it can lead to population declines and even extinction.
Habitat loss : This occurs when natural environments are destroyed or significantly altered. It's often due to human activities such as deforestation, urban development, agriculture, and mining. Habitat loss can result in local or even global extinction of species.
Fragmentation : This happens when a large, continuous area of habitat is divided into smaller, isolated patches, often as a result of human activities like road construction or clear-cutting for agriculture. Fragmentation can isolate populations of species, preventing gene flow and causing a decline in biodiversity.
While climate change (Option B) can also contribute to biodiversity loss, it is not the only cause, and likewise for over-exploitation (Option C) and habitat loss and fragmentation (Option D) alone. So, while these can all contribute to the problem, the option that includes all three (Option A) provides the most comprehensive answer to the question.

Turner syndrome are the presence of only a single X chromosome in females.

Some of the most common chromosomal abnormalities include:

• Down's syndrome or trisomy 21.
• Edward's syndrome or trisomy 18.
• Patau syndrome or trisomy 13.
• Klinefelter's syndrome or the presence of additional X chromosome in males.
• Turner syndrome are the presence of only a single X chromosome in females.
• XYY syndrome and XXX syndrome.

The Coenzyme is often a vitamin.

Coenzymes are small molecules. They cannot by themselves catalyze a reaction but they can help enzymes to do so. In technical terms, coenzymes are organic nonprotein molecules that bind with the protein molecule (apoenzyme) to form the active enzyme (holoenzyme).

A number of the water-soluble vitamins such as vitamins B1, B2 and B6 serve as coenzymes.

Viruses are exclusively parasites.

A virus cannot replicate outside a living cell. It requires a host body to complete its replication, without the host, it is considered Non-living. It lives in the host body as an obligate, intracellular parasite.They enter the host cells and captures all their metabolic activity.

Saprophytes: These are the organisms that depend on the dead and decaying matter to complete their food requirement. Eg. some fungi, slime mould and bacteria

Autotrophs: The organisms that prepare their own food are called autotrophs. These can be photo-autotrophs and chemo-autotrophs. Eg. Green plant, BGA

Meselson and Stahlexperimentally provedSemi conservative mode of DNA replication i.e., half of the DNA is conserved.

They used heavyisotope (nitrogen-15)and Cairns used radioactive thymidine. Due to thereplication of DNA, two DNA molecules were found in which50% radioactivitywas discovered.

When these twoDNA moleculeswere made to replicate, the next time four DNA molecules were produced. Out of this4 DNA, 2 DNA molecules were radioactiveand the other 2 are not. and after that also, theDNA moleculeswhich is obtained were further replicated then also thenumberof radioactive DNA was 2.

The embryo sac is produced from Megaspore.

A megaspore mother cell, or megasporocyte, is a diploid cell in plants in which meiosis will occur, resulting in the production of four haploid megaspores. In flowering plants the megasporangium is also called the nucellus, and the female gametophyte is sometimes called the embryo sac.

Endemic species are found exclusively in particular regions.

• These species are not naturally found anywhere else other than the areas where they are endemic.
• A particular type of animal or plant may be endemic to a zone, a state or a country.
• For e. g., Sal and Wild mango are two endemic species of Panchmarhi biosphere reserve.
• Bison, Indian giant squirrel and flying squirrel are endemic fauna of this area.