Tag: the origin of cells and cell division

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Multiple choice botany modes of reproduction introduction to flower pre fertilization - plants sexual reproduction in flowering plants the origin of cells and cell division

Entry of pollen tube in the ovule through integument is called

  1. Chalazogamy

  2. Basigamy

  3. Mesogamy

  4. Porogamy
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The entry of pollen tube in the ovule through integument is commonly known as mesogamy. It is commonly seen in plants like Cucurbita, Populus, etc.
So, the correct answer is 'Mesogamy'.
Multiple choice botany modes of reproduction introduction to flower pre fertilization - plants sexual reproduction in flowering plants the origin of cells and cell division

The apical growing region of pollen tube called

  1. Growing zone

  2. Cap block

  3. Non-vacuolate region

  4. Organelle region
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Apical zone of pollen tube contains abundant vesicles but lacks cell organelles. It is hemisphere in shape and transparent in nature. This transparent apical growing region of pollen tube is called as cap block. It exists only until the tube is growing. It disappears as soon as the growth ceases. 

Thus, the correct answer is option B. 

Multiple choice botany modes of reproduction introduction to flower pre fertilization - plants sexual reproduction in flowering plants the origin of cells and cell division

The functional part of the pollen tube is separate from the rest by

  1. Vacuoles

  2. Callose plugs

  3. Septa

  4. Both B and C
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Callose is a beta-1,3-glucan. It is the major component of the pollen tube cell wall. It is also deposited within the cytoplasm as distinct callose grains. This leads to the formation of callose plugs. Callose plugs separate the living, growing and functional part of the pollen tube in the tip from the remaining degenerating part.

Thus, the correct answer is option B.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Select the type of enzyme involved in the above reaction.

$\boxed{S - G + S' \rightarrow S + S' - G}$

  1. Dehydrogenase

  2. Transferase

  3. Hydrolase

  4. Lyase

  5. Isomerase
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Transferases are the enzymes that catalyze group transfer reactions. In the figure, one group G has been transferred to another group S'. It is a classical example of a group transfer reaction.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Who proposed the principle of "Induced fit"?

  1. Jacob

  2. Fischer

  3. Koshland

  4. Laderberg
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The induced-fit model is proposed by Daniel Koshland in 1958. It is the most accepted model for enzyme-substrate complex. It describes the formation of the Enzyme substrate as a result of the interaction between the substrate and a flexible active site which means exposure of an enzyme to a substrate causes the active site of the enzyme to change shape in order to allow the enzyme and substrate to bind. Hence option C is correct.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

DNA polymerase enzyme is responsible for the synthesis of

  1. DNA from RNA

  2. DNA from DNA

  3. RNA from DNA

  4. RNA from RNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

DNA polymerase is an enzyme used in DNA replication. It synthesizes DNA on a DNA template. Bacteria have three different DNA polymerases, i.e., DNA pol I, DNA pol II and DNA pol III; while eukaryotes have several DNA polymerase enzymes.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Basically how many types of enzymes have been recognised by International Union of Biochemistry?

  1. 4

  2. 5

  3. 6

  4. 8
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

According to the modern classification system given by International Union of Biochemistry, enzymes have been classified into six classes as follows :
Class First is Oxidoreductase.
Class Second is Transferase.
Class Third is Hydrolase.
Class Fourth is Lyase.
Class Fifth is Isomerase.
Class Sixth is Ligase.