MCQ
For question two statements are given $-$ one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion : Biodiversity loss is now one of the world's most pressing crisis.
Reason : Lower diversity in a species leads to non $-$ uniformity.
  • A
    Both assertion and reason are true and reason is the correct explanation of assertion.
  • B
    Both assertion and reason are true but reason is not the correct explanation of assertion.
  • Assertion is true but reason is false.
  • D
    Both assertion and reason are false.

Answer

Correct option: C.
Assertion is true but reason is false.
Lower diversity in a species leads to uniformity, as is the case with large monocultures of genetically similar crop plants.
This has advantage when increased crop production is a consideration, but can be a problem when an insect or a fungal disease attacks the field and poses a threat to the whole crop.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

Directions: In the following questions, the Assertions $(A)$ and Reason$(s) (R)$ have been put forward. Read both the statements carefully and choose the correct alternative from the following:
Assertion: Phenylketonuria is a recessive hereditary disease caused by body's failure to oxidise an amino acid phenylalanine to tryrosine, because of a defective enzyme.
Reason: It results the presence of phenylalanine acid in urine.
$\text{DNA}$ or $\text{RNA}$ segment tagged with a radioactive molecule is called $...........$
Directions: In the following questions, the Assertions $(A)$ and Reason$(s) (R)$ have been put forward. Read both the statements carefully and choose the correct alternative from the following:
Assertion: $\text{XX - XY}$ type of sex determination mechanism is an example of female heterogamety and is found in Drosophila.
Reason: Male heterogamety is seen in moths where males produce two different types of gamete.
For question two statements are given$-$one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion: Maximum biodiversity occurs in temperate areas.
Reason: Temperate areas have favourable conditions for speciation and for supporting variety and number of organisms.
Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion: Rhizobium forms nodules on the roots of legume plants.
Reason: Rhizobium fixes atmospheric nitrogen into organic forms which is used by the plant as nutrients.
For question, two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below. Assertion: $B-\text{DNA}$ has a constant diameter of $20 A.$
Reason: A pyrimidine always pairs with a purine.
Read the following and answer any four questions from $(i)$ to $(v)$ given below:
In angiosperms, the pollen grains are being transferred from the anther to the stigma and is termed pollination. This phenomenon was first discovered by Camerarius $(1694)$ in the end of seventeenth century. Pollen grains are immobile. They cannot reach the stigma by themselves. An external agent is required for this. The pollination is mainly of two types$-$self pollination and cross pollination. The diagram given below shows two plants of the same species showing different types of pollination.
  1. What is transferred between the plants in the process indicated by arrow $P?$
  1. Ova.
  2. Pollen.
  3. Nutrients.
  4. Seeds.
  1. Which of the following statements is correct regarding processes $P, Q$ and $R?$
  1. Processes $P, Q$ and $R$ introduce genetic variability in the offspring of sexually reproducing plants $X$ and $Y.$
  2. Wind serves as agent for process $Q$ if plants $X$ and $Y$ belong to Genus Salvia.
  3. Flowers of plants $X$ and $Y$ need to produce odour and nectar for completion of processes $P$ and $Q$ if they are entomophilous.
  4. If plants $X$ and $Y$ belong to Genus Cannabis, then their flowers need to produce sticky and heavy pollens in very small amount for accomplishment of process $Q.$
  1. Identify the processes $P, Q$ and $R.$
S. No $P$ $Q$ $R$
$(a)$
Geitonogamy
Xenogamy
Autogamy
$(b)$
Allogamy
Chasmogamy
Cleistogamy
$(c)$
Autogamy
Geitonogamy
Xenogamy
$(d)$
Geitonogamy
Allogamy
Autogamy
  1. In Catliarantl1us, the growth of style brings the stigma in contact of ripe anthers present on the mouth of corolla tube. This is an example of:
  1. Homogamy.
  2. Cleistogamy.
  3. Geitonogamy.
  4. Xenogamy.
  1. Which of the given processes represents a type of pollination that would result in greater adaptability of the particular species to potential environmental changes?
  1. $P.$
  2. $Q.$
  3. $R.$
  4. All of these.
For question, two statements are given$-$one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion: $\text{Z-DNA}$ follows a zig$-$zag course.
Reason: $\text{Z-DNA}$ is left handed.
For question two statements are given $-$ one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion : Kangaroo rat can live without drinking water.
Reason : This is an adaptation to water scarcity in arid conditions.
For question two statements are given $-$ one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion : Heliophytes, generally have low photosynthetic, respiratory and metabolic activities.
Reason : This is an adaptation of heliophytes to high intensity of light.