Test: Botany Mock Test - 1 - NEET MCQ

Megaspore mother cell is diploid so meiosis occurs in it.

Meiosis:

• In the metaphase stage, all the chromosomes are arranged at the cell equator. All the chromosomes have two chromatids, joined at the centromere. These are called sister chromatids. 
• The centromere splits in the anaphase stage and the two sister chromatids go to opposite poles. They are now called as chromosomes. They have single chromatid which will duplicate into two sister chromatids in the S phase. 
• Thus, at the anaphase stage number of chromosomes remains the same even as the number of chromatids is reduced to one-half due to the splitting of the centromere.

So, the correct answer is option D.

► Cell division is the basic requirement for the growth and development of the body, if the cells top dividing the body will eventually die.

There are two types of cell divisions:

• One occurs in the gamete cell and is necessary for reproduction as this cell division leads to genetic material exchange, this is meiosis or the reductional division.
• The other one is mitosis also known as Equational division which occurs in the somatic cells of the body and this cell division is employed in the repair of the body and increasing the number of cells for growth and development.

► In plants, mitosis occurs in the meristems which have the ability to divide continuously.

Meristems in plants are of two types:

• Apical meristems which are present on the tips of roots and shoots and they help in the elongation of length of the plant.
• The other is lateral meristem which helps in increasing the width of the plant.

Plants don’t repair or replace their damaged parts like leaves, branches but for new ones due to the continuous production of new cells in the meristems.

Mitosis in Onion Root Tips:

It is because they are the primary source of energy and every food chain starts with a producer because they produce their own food and pass energy for the other tropical level.

Sun is the ultimate source of energy and plants (producers) are the only ones who can convert sunlight into chemical energy. Hence producers bring energy into the ecosystem.

Monoecious” is translated as “single house,” meaning that male and female flowers are found on a single individual. This contrasts with the translation of dioecious, which is “double house.” This means that male flowers are on one plant and female flowers are on another plant.

• DNA helicase is responsible for opening up our DNA to allow for replication as well as the transcription of our DNA.
• A DNA helicase is an enzyme that functions by melting the hydrogen bonds that hold the DNA into the double helix structure. It is also known as Unwindase.
  

• Kornberg's success in unraveling the process of coenzyme synthesis established him as a biochemist by the early 1950s.
• It had also suggested to him that other large molecules such as the nucleic acids RNA and DNA would be synthesized in a similar way.
• He began his investigations into nucleic acid synthesis during the same years that James Watson and Francis Crick, among others, were trying to work out the likely structure of DNA.

• Exon is a part of gene that will become a part of final mature RNA produced by that gene after introns have been removed by RNA splicing.
• Cistron is the smallest unit of genetic material that must be intact to function as a transmitter of genetic information.
• A  codon is a sequence of three DNA or RNA nucleotides that corresponds with a specific amino acid (or stop signal) during protein synthesis.

An alternative form of a character in a pair, controlled by a single gene is called Allele. It is dominant either in a homozygous or heterozygous state.

The reason is simple. it was due to the monohybrid cross that Mendel could find that characters that we are not expressed in the F1 generation where expressed in the F2 generation .this could mean gametes independently contained alleles.

A white flower Sweet Potato(CCpp) is crossed with another white flowered Sweet Potato(ccPP). In the F1 generation, Purple flowered Sweet potato plants are formed. When these plants are subjected to self pollination, in the F₂ generation, 9 plants with purple flowers and 7 plants with white flowers are formed. It is complementary genes.

PS II occurs mostly on the granal lamellae of the chloroplast. PS II uses light energy for photolysis of H2O molecules, or oxidizing H2O molecules producing electrons, protons (H+) and O2.

• Reproduction by conidia occurs in Ascomyctes of fungi.
• The body of fungi is called mycelium.
• The asexual spores are conidia produced exogenously on the special mycelium called conidiophores.
• Conidia on germination produced mycelium.

Thereby Asexual reproduction by conidia occurs in penicillium.

Photosynthesis in plants converts solar energy into chemical energy using electrons and protons from water.

Fungi are classified as per their modes of  nutrition as 
1. Saprophytic
2. Parasitic
3. Symbiotic (Mycorrhiza)
Saprophytic Fungi:
These fungi feed on dead organic matter and decaying matter.
Parasitic Fungi:
Parasitic fungi live or colonise animals, plants and other fungi living on their expenses, inflict diseases or even death.
Symbiotic (Mycorrhiza):
The mycelium feeds on organic compounds in the soil substrate through decomposition or through particular associations with plants.

When light is incident on chloroplast, firstly exciting of an electron and then next reactions will occur.

When stamens are attached to the petals, they are epipetalous as in brinjal, or epiphyllous when attached to the perianth as in the flowers of lily.

If the supply of oxygen is decreased to an illuminated wheat plant, its photosynthesis would increase.

Photosynthesis: 

• The leaves have a green pigment called chlorophyll.
• It helps leaves to capture the energy of the sunlight.
• This energy is used to synthesise (prepare) food from carbon dioxide and water. Since the synthesis of food occurs in the presence of sunlight, it is called photosynthesis.

In the presence of sunlight Carbon dioxide + water → Carbohydrate + oxygen.

• Some plants, green algae, and cyanobacteria can perform photosynthesis.
• The process of photosynthesis is commonly written as

                   6CO₂ + 6H₂O + Sun-Light → C₆H₁₂O₆ + 6O₂

Plant cells have a cell wall to protect them and make them rigid structure.

• Flowers contain the plant’s reproductive structures.
• A typical flower has four main parts - or whorls - known as the calyx, corolla, androecium, and gynoecium.
• The outermost whorl of the flower has green, leafy structures known as sepals.
  • The sepals, collectively called the calyx, help to protect the unopened bud.

Lead always impaire our nervous system when anyway it enters in our body.

Tapetum synthesizes callase enzyme which dissolves callose. It produces many hormones ,amino acids and nutrious substances that are needed for pollen grains.

The primary function of rhizoids in mosses is for anchorage and absorption. Rhizoids are hair-like structures that help mosses attach to their substrate and absorb water and nutrients from the environment. Unlike roots, they do not have a vascular system but are crucial for the stability and survival of mosses in their habitats.

• Chlamydomonas is found in stagnant water and on damp soil as well as freshwater, seawater, and even in snow.
• About Chlamydomonas-
  • Class: Chlorophyceae
  • Order: Chlamydomonadales
  • Scientific name: Chlamydomonas
  • Phylum: Chlorophyta
  • Higher classification: Chlamydomonadaceae

Angiosperms are known for having a double fertilization process. This unique feature involves two sperm cells; one fertilizes the egg to form the zygote, while the other fuses with two polar nuclei to form the triploid endosperm, which nourishes the developing embryo. Double fertilization is a key characteristic that distinguishes angiosperms from other plant groups.

Adenosine triphosphate (ATP) is a complex organic chemical that provides energy to drive many processes in living cells, e.g. muscle contraction, nerve impulse propagation, and chemical synthesis. Found in all forms of life, ATP is often referred to as the "molecular unit of currency" of intracellular energy transfer

Chlorophyll a is considered the primary photosynthetic pigment because it is directly involved in the conversion of light energy into chemical energy during photosynthesis. It acts as the central molecule in the light-harvesting complex, capturing light and initiating the process of energy conversion. Interesting fact: Despite the presence of other pigments, chlorophyll a's unique role makes it indispensable for the photosynthetic process across all photosynthetic plants.

The light-harvesting complex captures light energy and transfers it to the reaction center, where photosynthesis's photochemical reactions begin. This complex, consisting of various pigment molecules bound to proteins, ensures efficient light absorption and energy transfer, enhancing the overall efficiency of photosynthesis. Interesting fact: The diversity of pigments in the light-harvesting complex allows plants to utilize a broader spectrum of sunlight, from blue to red wavelengths.

Ruben and Kamen's experiment confirmed that the oxygen evolved during photosynthesis comes from water, not from carbon dioxide. They used water containing the heavy isotope of oxygen (¹⁸O) to trace the origin of oxygen released during photosynthesis. Interesting fact: This experiment was pivotal in understanding the photosynthetic water-splitting process, highlighting the role of water as the electron donor in the light reactions.