NEET Part Test - 8 - NEET MCQ

• Viruses are acellular, which means they don't have a cellular structure.
• Bacteriophages are viruses that infect the simplest living species and are one of the most complex virus particles.

Hence, the correct option is B
NCERT Reference: Topic- VIRUSES, VIROIDS, PRIONS AND LICHENS of chapter "Biological Classification" of NCERT.

Prokaryotes differ from Eukaryotes in absence of nuclear membrane and membrane-bounded organelles like mitochondria, Golgi bodies etc.

Hence, the correct option is C
NCERT Reference: Topic- Characteristics of the Five Kingdoms” of chapter "Biological Classification" of NCERT.

Double helix model of DNA was proposed by James Watson and Francis Crick in 1953 based on X-ray diffraction data produced by Maurice Wilkins and Rosalind Franklin.

Proteins human haemoglobin consists of 4 subunits. Two of these are identical toeach other. Hence, two subunits of αα type and two subunits of ββ type together constitute the human haemoglobin (Hb).

The paired bases are stacked on the inside of the double helix with one base pair is every 3.4 angstrom. Now the distance between 23 base pair are (3.4) ×23 =78.2 angstrom.

According to Chargaff's base pair rule, DNA from any cell of an organism should have a 1:1 ratio of pyrimidine and purine bases, that is, the total amount of purines = total amount of pyrimidines.  In this, the amount of guanine is equal to the amount of cytosine and the amount of adenine is equal to the amount of thymine. The ratio of A: T = 1 and the ratio of G: C = 1. According to Chargaff's rule, G + C / A + T ratio varies with the species but is constant for a species. 

• There are 20 naturally occurring amino acids.
• All the amino acids except glycine are chiral. Amino acids are classified as acidic, basic or neutral based on the relative number of amino and carboxylic groups.
• Amino acids are classified as essential amino acids and non-essential based on whether they are synthesized in the body or not.

• Proteins are polymers of amino acids undergo dehydration to form a peptide linkage.
• Dipeptides are formed by a single peptide bond and a tripeptide through two peptide bonds and so on.

It is a polypeptide of 27 amino acids. It is secreted by cells in the duodenum when they are exposed to the acidic contents of the emptying stomach. It stimulates the exocrine portion of the pancreas to secrete bicarbonate into the pancreatic fluid (thus neutralizing the acidity of the intestinal contents).

Because if there will be a rise in blood pressure ultimately the heart beat rises and ADH is secreted when there is loss of water (it can be taken as adverse conditions)

Both are required in small amount.
Enzymes present very low amount in the cell and they do not altered during reaction.a small amount of enzyme can catalyze between 1 to 1000 molecules substrate per hour.
Hormones: The main function of endocrine gland is to secrete hormones directly into bloodstream. Very small amount of hormones can trigger very large response in the body.each type of hormone influences only certain organ and tissue.

When it comes to hydration, water is the best option for people with diabetes. That's because it won't raise your blood sugar levels. High blood sugar levels can cause dehydration. Drinking enough water can help your body eliminate excess glucose through urine.

CCK-PZ (cholecystokinin- pancreozymin) is secreted by endocrine cells of the duodenal wall in response to the presence of fatty food. It induces contraction of the gallbladder to release stored bile. Adrenocorticotropic hormone (ACTH) targets adrenal cortex to produce its hormones. LTH (luteotropic hormone/prolactin) targets mammary gland to stimulate breast development and milk production after baby birth. FSH stimulates growth and development of follicles in the ovary. Thus, the correct answer is A.

The posterior pituitary is often termed the neurohypophysis because the hormones of this part of the pituitary are released directly from the axonal endings of their source neurons into the circulation.

Secretion of the posterior pituitary hormones is directly from magnacellular neurons of the paraventricular and supraoptic nuclei into the circulation. These neurons project axons into the posterior pituitary via the hypothalamo-neurohypophyseal tract and terminate on a capillary bed of the inferior hypophyseal artery. Control of release in this system is under neural control and so this represents a reflex system with neural input and hormonal output.

• The exine of the pollen grain is made of sporopollenin. Sporopollenin is one of the most resistant organic compounds.
• It can withstand high temperature, strong acids, and alkalis and cannot be degraded by any of the known enzymes.
• Hence, it acts as a shield and protects the pollen grain from getting damaged.

Structure of pollen grain:

Hence the correct option is 'A' 

The bilobed nature of an anther is distinct in a transverse section due to the presence of microsporangia located at the corners of each lobe.

The assertion correctly states that the stigma serves as a landing platform for pollen grains. The reason also correctly states that the stigma has fine hairs (which are part of the stigma's structure) that aid in trapping pollen grains, providing a logical explanation for the assertion.

The first word in a biological name represents the genus while the second word denotes the specific epithet.

Hence, the Correct Answer is C

NCERT Reference: Topic- Nomenclature from chapter "The Living world" of NCERT.

Higher taxonomic categories, like phylum, encompass a broader diversity of organisms, sharing more general characteristics compared to the more specific and closely related organisms grouped within lower categories like species and genus. This reflects the hierarchical nature of biological classification, where each ascending level represents a broader grouping based on less specific shared traits.

This is the correct taxonomic hierarchy from the broadest to the most specific category:

Kingdom > Phylum > Class > Order > Family > Genus > Species.

In this hierarchy, the broadest category is Kingdom, which groups organisms based on general similarities. As we move down the hierarchy, each category becomes more specific, ending with the most specific category, Species.

Hence, the Correct Answer is C
NCERT Reference: Topic- Taxonomic hierarchy from chapter "The Living world" of NCERT.

• Animals that belong to the phylum Platyhelminthes to Chordata are all triploblastic.
• But Platyhelminthes and aschelminthes belong to pseudocoelomates.
• Annelids, arthropods, echinoderms and chordates are under eucoelomates. This means not all triploblastic animals are eucoelomates. 
• Pseudocoelomates have false coelom while eucoelomate animals only have the true coelom. 

Hence, both statement 1 and statement 2 are incorrect. 

Platyhelminthes are triploblastic, acoelomate organism showing bilateral symmetry. Ctenophores have borads symmetry, are acoelomates having diploblastic organisation. In echinoderms, larvae have bilateral symmetry whiled add have radial symmetry. They are coelomates with triplobla organisation. Annelids are triploblastic, coelomaterorganism showing bilateral symmetry.

Answer: A

Solution: The endosymbiotic theory suggests that cyanobacteria, through a symbiotic relationship with early eukaryotic cells, gave rise to the chloroplasts found in modern plants. The presence of chlorophyll a in both cyanobacteria and chloroplasts supports this theory, making the reason a correct explanation of the assertion

The animals in which the coelom is absent are called acoelomates, for example flatworms (Planaria). In them the space between ectoderm and endodorm is filled with parenchyma derived from mesoderm.

(i) A microsporangium or future pollen sac is a cylindrical sac that appears circular in the transverse section. It consists of two parts, the outer wall, and central homogeneous sporogenous tissue. 
(ii) Microsporangial wall has four types of layers - epidermis, endothecium, 1−3 middle layers, and tapetum. 
(iii) The outer three layers perform the function of protection in the young anther and mechanism of dehiscence in the ripe anther. 

Autogamy (Gk. autos-self, gamos-marriage) is a type of self-pollination in which an intersexual or perfect flower is pollinated by its own pollen.

Geitonogamy is a type of pollination in which pollen grains of one flower are transferred to the stigma of another flower belonging to either the same plant or a genetically similar plant. In geitonogamy, the flowers often show modifications similar to ones found in xenogamy or cross-pollination.

Xenogamy or cross-pollination is the transfer of pollen grains from the anther of one flower to the stigma of a genetically different flower.

Monoecious plant species have separate male and female flowers on the same plant. Examples or monoecious plants are castor, maize, birch, coconut and cucurbit. The plants in which male and female flowers are borne on separate individual are referred to as dioecious plants. e.g., papaya, date palm.

• Pollen grain protoplasts are uninucleate at the beginning but at the time of liberation it becomes 2 or 3 celled.
• Pollen grains are the male gametes.
• They are present inside the pollen sacs.

• The ovule bearing parenchymatous tissue is known as the placenta.
• It is also the part of the ovary where the funiculus attaches itself.
• Just like in humans, the placenta provides nutrition to the growing ovules.

The development of the male gametophyte in angiosperms is called as microgametogenesis. Pollen grain is the first cell of a male gametophyte. This cell undergoes only two divisions, with the result of first division two cells are formed - a large vegetative cell and a small generative cell. The second division is concerned with generative cell only. This division may take place either in pollen grain or in the pollen tube and gives rise to two male gametes.