Tag: concept of life

Questions Related to concept of life

Which of the following statements is true?

biology concept of life theories of the origin of life origin of life the origin of cells and cell division

  1. True cell evolved before the protocell

  2. Prokaryotes evolved before eukaryotes

  3. Eukaryotes evolved before prokaryotes

  4. Prokaryotes didnt evolve until 1.5 billion years ago

Show answer
Correct Option: B
Explanation:

  • Scientists have concluded that prokaryotic life forms preceded the more complex eukaryotes. 
  • All organisms on Earth are classified into two basic cell types. "Kary" means nucleus, "Pro" means "before," and prokaryotes have DNA in a freely floating ring that is not encased in a nucleus. 
  • "Eu" means "true," and eukaryotes have DNA arranged in chromosomes and encased in a nucleus. 
  • Fossil evidence indicates that prokaryotic cells first existed on the earth, prior to the arrival of the eukaryotes. 
  • Though they lack skeletons, a few groups of single-celled organisms have hard portions or secrete hard shells and so appear in the fossil record. 
  • This record is the best indication of prokaryotes' and eukaryotes' relative ages.
So the correct option is 'prokaryotes evolved before eukaryotes'.

The term, reducing atmosphere for the early earth means that the atmosphere

biology concept of life theories of the origin of life origin of life the origin of cells and cell division

  1. Was much thinner around the surface of the earth than now

  2. Contained only two or three kinds of gases

  3. Contained little or no free oxygen

  4. Contained little or no free nitrogen

Show answer
Correct Option: C
Explanation:
Scientists believe that the Earth was formed about 4.5 billion years ago. Its early atmosphere was probably formed from the gases given out by volcanoes. It is believed that there was intense volcanic activity for the first billion years of the Earth's existence. The early atmosphere was probably mostly carbon dioxide, with little or no oxygen. There were smaller proportions of water vapour, ammonia and methane.
So the correct option is 'contained little or no free oxygen'.

Members of biologic species are potentially able to

biology concept of life theories of the origin of life origin of life the origin of cells and cell division

  1. compete

  2. introgress

  3. interbreed

  4. express all the same genes

Show answer
Correct Option: C
Explanation:

Species are groups of actually or potentially interbreeding populations which are reproductively isolated from other such groups. Interbreeding also called as hybrid is the result of combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction. 

So the correct option is 'interbreed'.

Who first proposed the term and concept of species?

biology concept of life theories of the origin of life origin of life the origin of cells and cell division

  1. John Ray and Ernst Mayr

  2. John Ray

  3. Lamarck and Darwin

  4. Ernst Mayr

Show answer
Correct Option: D

Which was absent in the atmosphere at the time of origin of life?

biology concept of life theories of the origin of life origin of life the origin of cells and cell division

  1. $NH _3$

  2. $H _2$

  3. $O _2$

  4. $CH _2$

Show answer
Correct Option: C

The first person who proposed that small organic molecules can be formed in and oxygen-deprived environment was

biology concept of life theories of the origin of life origin of life the origin of cells and cell division

  1. Stanley Miller

  2. Thomas Cech

  3. Aleksander

  4. Sidney Fox

Show answer
Correct Option: C
Explanation:

In 1924, the Russian biochemist Aleksandr Oparin proposed that life could have developed through gradual chemical evolution in a “primordial soup.” This theory was independently proposed by English geneticist J.B.S. Haldane, also in the 1920s. This theory states that a mixture of organic molecules could form in an oxygen-deprived environment through the random interactions of small molecules, with energy provided by sunlight and lightning. This theory is not without controversy. 

So the correct option is 'Aleksander'.

During which of the following intervals did life originate on the Earth?

biology concept of life theories of the origin of life origin of life the origin of cells and cell division

  1. Mesozoic era

  2. Proterozoic eon

  3. Cambrian period

  4. Archean eon

Show answer
Correct Option: D
Explanation:
  • The Archean (or Archaean) eon is an interval of geologic time of about 1.4 billion years, beginning with the formation of Earth's crust and the oldest Earth rocks 3,960-3,800 million years ago (mya) and continuing until its boundary at 2,500 mya, with the Proterozoic eon. 
  • The origin of life has been traced to the Archean eon, with fossils of prokaryotes.
  •  During the Archean eon, prokaryotes spread over much of Earth's surface, often in mats comprising myriads of collaborating bacteria differentiated by the type of biochemistry each performed. 
  • During the Archean eon some prokaryotes developed the molecular structures for achieving photosynthesis, which permitted them initially to use sunlight for capturing hydrogen from the atmosphere and later to use it for capturing carbon from atmospheric carbon dioxide with the release of oxygen, thus helping to prepare an environment that could support eukaryotic cells and multicellular forms of life.
So the correct option is 'Archean eon'.

The first genes may have developed when

biology concept of life theories of the origin of life origin of life the origin of cells and cell division

  1. Protobionts grew and divided

  2. Short RNA strands self-replicated

  3. DNA molecules produced RNA molecules

  4. Polypeptides became catalytic

Show answer
Correct Option: B
Explanation:

RNA is capable of catalyzing a number of chemical reactions, including the polymerization of nucleotides. RNA is uniquely able both to serve as a template for and to catalyze its own replication. Consequently, RNA is generally believed to have been the initial genetic system, and an early stage of chemical evolution is thought to have been based on self-replicating RNA molecules—a period of evolution known as the RNA world.

So the correct option is 'short RNA strands self-replicated'.

Transformation of the early reducing atmosphere of the earth into an oxidizing atmosphere was mainly due to the activities of

zoology concept of life theories of the origin of life origin of life the origin of cells and cell division

  1. Aerobic photosynthesizers

  2. Anaerobic heterotrophs

  3. Anaerobic photosynthesizers

  4. Anaerobic chemoheterotrophs

Show answer
Correct Option: A
Explanation:

Cyanobacteria are thought to be the first aerobic photosynthesizers evolved which gradually increased the oxygen portion of atmosphere changing it into oxidising one. The aerobic respiration was thus helpful for the animals to survive.

Thus, the correct answer is option A.