CBSE 12TH BIOLOGY - Online Test
Q1. Which of the following is not correct about artificial means of vegetative propagation
Answer : Option B
Explaination / Solution:
During vegetative propagation, new organisms are formed by single plant parts. So, new individuals are genetically similar to each other and there is no genetic variation.
Q2. The scientist who put price tag of US$ 33 trillion a year for nature’s life-support services was
Answer : Option C
Explaination / Solution:
Robert Costanza is the director and founder of the Gund Institute for Ecological Economics at the University of Vermont, and cofounder of the International Society for Ecological Economics.
In 1997, Costanza and his colleagues made news headlines around the world with a paper, published in the British journal Nature, that estimated the annual net worth of the biosphere: $33 trillion, a figure greater than the annual gross national products (GNP) of all the world’s economies combined.
Q3. Dolly sheep was produced due to property of the cells called as
Answer : Option D
Explaination / Solution:
The cells of embryo are totipotent that means that they have ability to produce whole new organism form single cell. Dolly sheep was produced due to property of totipotency.
Q4. The percentage of ratio of natality over mortality is called
Answer : Option B
Explaination / Solution:
Natality is the total number of new population added into existing population by birth on the other hand mortality means no of death in a particular geographical area or population. The ratio of natality and mortality is called vital index.
Q5. The fertilisation in which male gametes are carried through pollen tube is called as
Answer : Option D
Explaination / Solution:
Pollen grain lands on stigma for pollination. The pollen grain germinates and moves towards egg through pollen tube. This male and female gamete fusion is called siphonogamy.
Q6. Mediterranean orchid Ophrysensures pollination by
Answer : Option C
Explaination / Solution:
Mediterranean orchid Ophrys ensures pollination by co-evolution, sexual deceit and pseudo-copulation. One petal of flower bears an uncanny resemblance to female of bee in size, colour and markings.
Q7. Carcinoma refers to
Answer : Option A
Explaination / Solution:
Carcinoma is a type of cancer or Malignant tumors of the skin or mucous membrane that starts in cells that make up the skin or the tissue lining organs, such as the liver or kidneys.
The physical, chemical or biological agents that convert normal cell into cancerous cell are called carcinogens.
Q8. Number of nitrogenous bases in a Codon is
Answer : Option B
Explaination / Solution:
A codon is a sequence of 3 nitrogenous bases located on mRNA that will pair up with the anticodon of tRNA to make the polypeptide (protein) I. 64 codons can be obtained from four nitrogenous bases if arranged in group of 3.
Q9. The capacity to generate a whole plant from any cell/ explant is called
Answer : Option B
Explaination / Solution:
The ability to generate a whole plant from any cell/explant is called totipotency. Tissue culture method is used to generate whole plant from plant parts.
Q10. If a species experiences a 90 percent decline over 10 years (or three generations), would be classified as :
Answer : Option B
Explaination / Solution:
A critically endangered (CR) species is one which has been categorized by the International Union for Conservation of Nature (IUCN) as facing a very high risk of extinction in the wild.
Criteria for critically endangered is an observed, estimated, inferred or suspected population size reduction of ≥ 90% over the last 10 years or three generations, whichever is the longer, where the causes of the reduction are clearly reversible AND understood AND ceased.
Critically endangered species should be protected to avoid extinction.
