Tag: botany

Questions Related to botany

Choose the correct answers from the alternatives given.
Annual rings are the number of

botany stem - external morphology habit of plants plant classifications type of plants

  1. Rings of vascular bundles in a monocot stem

  2. Layers of secondary xylem in a stem

  3. Internodes in a stem

  4. Both (b) and (c)

Show answer
Correct Option: B
Explanation:

Each year, the tree forms new cells, arranged in concentric circles called annual rings or annual growth rings. These annual rings show the amount of wood produced during one growing season. As the stem grows, complete ring called the cambial ring is formed. Cambial ring leads to the formation of secondary xylem and secondary phloem. 

Hence, the correct answer is 'Layers of secondary xylem in a stem'.

Choose the correct answers from the alternatives given.
During the secondary growth in the dicotyledonous stems the cork cambium gives rise to

botany stem - external morphology habit of plants plant classifications type of plants

  1. Secondary xylem and secondary phloem

  2. Secondary cortex and cork

  3. Pith and medullary rays

  4. Multicellular hairs

Show answer
Correct Option: B
Explanation:

Cork cambium is a tissue found in many vascular plants as part of the epidermis. The cork cambium is a lateral meristem and is responsible for secondary growth that replaces the epidermis in roots and stems. It gives rise to cork outside and secondary cortex inside. 

Hence, the correct answer is 'Secondary cortex and cork'.

Which is the source of variations?

botany classical genetics variation and its type natural selection introduction to genetics

  1. Mutation

  2. Recombination

  3. Deletion

  4. All of the above

Show answer
Correct Option: D
Explanation:

Mutations, recombinations and deletions all are the sources of genetic variation. A Mutation occurs when a DNA gene is damaged or changed in such a way as to alter the genetic message carried by that gene. Recombination involves the exchange of genetic material either between multiple chromosomes or between different regions of the same chromosome. Deletion is a mutation in which a part of a chromosome or a DNA sequence is missing. 

The variations are caused by 

botany classical genetics variation and its type natural selection introduction to genetics

  1. Internal changes

  2. Environment

  3. Hybridization

  4. All of the above

Show answer
Correct Option: D
Explanation:

Variations can be defined as the difference in characters among the individuals of same species, it gets affected by internal changes, environmental changes, hybridization etc.

So, the correct answer is "All of the above".

Which is a source of variation and genetic diversity that is shared between prokaryotes and eukaryotes?

botany classical genetics variation and its type natural selection introduction to genetics

  1. Random fertilization involving a unique sperm and a unique egg

  2. Independent assortment of each chromosome pair during metaphase I of meiosis

  3. Crossing-over during prophase I of meiosis

  4. Random mutation

Show answer
Correct Option: D
Explanation:

The genetic material in prokaryotes is not confined into a nucleus and they do not have a nuclear membrane and the genetic material is present in the form of chromatin and cytoplasm and there is no chance of crossing over during meiosis and no fertilization but random mutations do arise in them and it results change in the genetic material.

So, the correct option is 'Random mutation'

The major/ ultimate source of variations are

botany classical genetics variation and its type natural selection introduction to genetics

  1. Polyploidy

  2. Mutations

  3. Chromosome aberrations

  4. Segregation

Show answer
Correct Option: B
Explanation:
Ultimate source of variation is MUTATION and nothing else. Mutations are mistakes that occur in DNA sequence of genome:
  • Point mutation e.g. nonsense and missense mutations
  • Frame-shift mutation e.g. insertion or deletion mutations
Any change in genetic DNA will be translated into a defect in the corresponding protein. Thus mutation is responsible for appearance of a phenotypic variation. Such a variation may help the organisms carrying the new variation to survive better. If it produces more progeny the variation will appear in more members. Variations which provide adaptive advantage get selected by nature, thus help organisms to evolve.

So, the correct answer is 'Mutations'.

Cannibals feed on

botany classical genetics variation and its type natural selection introduction to genetics

  1. Carcases

  2. Blood

  3. Carnivores

  4. Members of own species

Show answer
Correct Option: D

Discontinuous variations are :

botany classical genetics variation and its type natural selection introduction to genetics

  1. Essential features

  2. Acquired character

  3. Non-essential changes

  4. Mutations

Show answer
Correct Option: D
Explanation:
Discontinuous variations are where individuals fall into a number of distinct classes or categories and are based on features that cannot be measured across a complete range. You either have the characteristic or you don't. 
Discontinuous variation is controlled by alleles of a single gene or a small number of genes. As variations caused by mutations affect DNA in such a way that either organism has a certain characteristic resulting from mutation or not, it is an example of discontinuous variations.
So, the correct answer is 'Mutations'

Height in humans is

botany classical genetics variation and its type natural selection introduction to genetics

  1. Somatogenic variation

  2. Discontinuous variation

  3. Continuous variation

  4. Both B and C

Show answer
Correct Option: C
Explanation:

A.Somatogenic variation – These are acquired variations and non inheritable in nature. Eg:phenotypic plasticiy.

B.Discontinuous variations – These are responsible for the formation of a new species and the organism, thus, formed is called mutant. Eg:Mutations.

C.Continuous variations – These are fluctuating variations and cannot give rise to new species. Eg:Human height.

So, the correct option is ‘Continuous variations’.

Primary source of allelic variation is

botany classical genetics variation and its type natural selection introduction to genetics

  1. Independent assortment

  2. Recombination

  3. Mutation

  4. Polyploidy

Show answer
Correct Option: B
Explanation:

Primary source of allelic variation is recombination. Recombination is the natural process of breaking and rejoining DNA strands to produce new combinations of genes and, thus, generate genetic variation. This is the phenomenon that occurs during meiosis I.


So, the correct answer is 'Recombination'.