Download App

Human Health and Disease — BIOLOGY STD 12 Science — Question

Maharashtra BoardEnglish MediumSTD 12 ScienceBIOLOGYHuman Health and Disease1 Mark
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 : Skin forms the first tine of defence.
Reason: It is a non$-$specific defence.
  • A
    Both assertion and reason are true and reason is the correct explanation of assertion.
  • ✓
    Both assertion and reason are true but reason is not the correct explanation of assertion.
  • C
    Assertion is true but reason is false.
  • D
    Both assertion and reason are false.
✓

Answer

Correct option: B.
Both assertion and reason are true but reason is not the correct explanation of assertion.
Skin acts as the first line of defence because it provides a protective covering to the body against the entry of microorganisms. Its action is not specific to a particular organism. Skin forms the first$-$line of defence because $-$ It forms the hard, keratinized outer layer of the body and form effective barrier for most bacteria and viruses. The secretion of oil and sweat glands make the surface $pH$ acidic which does not let microorganisms to survive for long.The salts and fatty acids present in perspiration contain lysosomes that destroy the bacterial cell wall. It contains friendly bacteria, also release acids and other metabolic wastes which also inhibit the multiplication of organisms.

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

Explore more

More "Assertion (A) & Reason (B) MCQ" from Human Health and Disease→Human Health and Disease — all question types→BIOLOGY STD 12 Science question papers→Maharashtra Board STD 12 Science question papers→Maharashtra Board question paper generator→

Similar questions

For question two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $\text{(a), (b), (c)}$ and $(d)$ as given below.
Assertion : The principle of segregation given by Mendel is the principle of purity of gametes.
Reason : Gametes are pure for a character.
→
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: Aspergillus niger produces lactic acid.
Reason: Rhizopus produces citric acid.
→
For 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: Self-sterility inhibits self$-$pollination.
Reason: Dichogamy is the condition in which only self$-$pollination occurs.
→
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: Amensalism is a negative interaction between two living individuals.
Reason: In amensalism, allochemics are secreted by one individual.
→
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: Bacteriophage vectors are more advantageous than plasmid vectors.
Reason: Bacteriophage vectors can be easily detected at the time of cloning experiments.
→
Read the following and answer any four questions from $(i)$ to $(v)$ given below:
Cross pollination is the transfer of pollen grains from the anther of a one flower to the stigma of a genetically different flower. It is performed with the help of an external agency which may be abiotic $($e.g., wind, water$)$ or biotic $($e.g., insects, birds, bats, snails$)$. The diagram shows the carpel of an insect pollinated flower.
  1. What is the most likely reason for non germination of pollen grain $Z$ ?
  1. Pollen grains $X$ and $Y$ were brought to the stigma earlier, therefore, their germination inhibited the germination of pollen grain $Z$.
  2. Pollen grain $Z$ was brought to the flower by wind, while pollen grains $X$ and $Y$ were brought to the flower by insect.
  3. Pollen grain $Z$ lacks protrusions that allow it to adhere properly onto the stigma surface.
  4. Pollen grain $Z$ comes from a flower of an incompatible species.
  1. Which of the following best describes the function of the pollen tube?
  1. It acts as a conduit to transport male gametes from the anther to the ovule.
  2. It acts as a conduit to transport male gametes from the stigma to the ovule.
  3. It contains key nutrients that serve to nourish the newly $-$ formed zygote.
  4. It digests the tissues of the stigma, style, and ovary.
  1. Pollination of a flower in which the pollen is carried by an insect is called:
  1. Anemophily.
  2. Ornithophily.
  3. Entomophily.
  4. Malacophil.
  1. Refer to the given characteristics of some flowers.
  1. The stamens hang out of the flower, exposing the anthers to the wind.
  2. The pollen grains are tiny and light.
  3. The flower has a sweet scent.
  4. The flower petals are brightly colored.
  1. Pollenkitt is generally found in:
  1. Anemophilous flowers.
  2. Entomophilous flowers.
  3. Ornithophilous flowers.
  4. Malacophilous flowers.
→
For 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: Perisperm is protective covering of seed and helps in dispersal and nutrition.
Reason: Pericarp is covering of fruit which is non$-$functional.
→
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 : $\text{SCID}$ is the first genetic disorder to be combated with gene therapy.
Reason : $\text{SCID}$ is a type of allergy.
→
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 : Constitutive genes are continuously being expressed.
Reason : Constitutive genes are frequently needed for various metabolic functions.
→
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 : Cuscuta is an example of holoparasite.
Reason : Cuscuta does not depend on other plants for nutrition requirements.
→