Cylindrical bodied, worm-like marine animals belong to the phylum: a) Echinodermata b) Mollusca c) Coelenterata d) Hemichordata

Question:

Cylindrical bodied, worm-like marine animals belong to the phylum: 

a) Echinodermata 

b) Mollusca 

c) Coelenterata 

d) Hemichordata

Answer: option (d) "Hemichordata".

Explanation: 

Solution: (a) Characteristics of Echinodermata: They have a star-like appearance and are spherical or elongated. They are exclusively marine animals. The organisms are spiny-skinned. They exhibit organ level of organization. 

(b) characteristics of phylum Mollusca: They are mostly found in marine and freshwater. Very few are terrestrial and found in moist soil. They exhibit organ system level of organization. Their body has a cavity. The body is divided into head, visceral mass, muscular foot and mantle. 

(c) characteristics of phylum Coelenterata: These are mostly aquatic or marine habitat animals. These species exhibit a tissue-level organization. The mouth is enclosed by thin and short tentacles. They are diploblastic animals, in which, the body is made up of two layers of cells: Ectoderm - One layer makes up the cells outside the body Endoderm - the other forms the inner lining of the body.

(d) characteristics of phylum Hemichordata: Phylum Hemichordata consists of a small group of worm-like marine animals. They have organ-system level of organization, bilaterally symmetrical, triploblastic and coelomate animals. The body is cylindrical and is composed of an anterior proboscis, a collar and a long trunk. 

Hence, the correct answer is option (d) "Hemichordata".

In which of the following does active transport take place? (A) Pumps (C) Ion channels (B) Carrier protein transport (D) Diffusion

Question:

In which of the following does active transport take place? 

(A) Pumps 

(C) Ion channels 

(B) Carrier protein transport 

(D) Diffusion

Answer: option (A) Pumps 

Explanation:

Pumps are a kind of active transport which pump ions and molecules against their concentration gradient. Active transport requires energy input in the form of ATP. Much like passive diffusion, protein pumps are specific for certain molecules. The sodium-potassium pump is one of the most significant transport proteins. It's the protein that allows your nerves to pass electrical charges so they function. The sodium-potassium pump works by transporting sodium and potassium against their concentration gradients. This basically means that it pumps these ions from areas of low concentrations (few ions) to areas of high concentration (many ions). The protein channels that undergo passive transport work against the pump, allowing sodium ions to enter the cell constantly, so the pumps work to remove the excess ions. 

So, correct answer is pumps in which Active transport take place.

Production of seed without fertilization is called as- (A) Polyembryony (B) Apomixis (C) Parthenocarpy (D) Apospory

Question:

Production of seed without fertilization is called as- 

(A) Polyembryony 

(B) Apomixis 

(C) Parthenocarpy 

(D) Apospory 

Answer: option (B) "Apomixis"

Explanation:

Apomixis refers to the formation of the plant from a seed without fertilization. Apomixis is very common in higher plants. Apomixis can be best described as the reference to the asexual process. The plant produced is a clone of the female parent plant. Examples of apomixis: Cereals, Rosaceae, Compositae, Rutaceae and wheat, are some examples of Apomixis. So, Apomixis is the development of a seed without fertilization. Apomixis is a type of asexual reproduction which mimics sexual reproduction. 

Hence, the correct answer is option (B) "Apomixis".

In some plants where flowering occurs more than once what would you will call the inter flowering period:(A) Juvenile (B) Mature (C) Senescent (D) Aging

Question:

In some plants where flowering occurs more than once what would you will call the inter flowering period:

(A) Juvenile 

(B) Mature 

(C) Senescent 

(D) Aging 

Answer: option (A) Juvenile

Explanation:

Option A : The plants which flower more than once, their inter - flowering period represents the juvenile phase. Although they pass the mature phase of flowering for the first time. But for flowering for the next time, they require further development. Therefore this is the correct option.

Option B: Mature phase of a plant is when it has the ability to flower and reproduce. In plants where flowering occurs more than once, the plant regresses back to the juvenile phase before it flowers again. Therefore this is an incorrect option. 

Option C: Senescent phase marks the end of the reproductive phase of the plant. Senescent phase signifies that after this phase the plant cannot reproduce. Therefore this is an incorrect option. 

Option D:Plant senescence is the process of aging in plants. Plants have both stress-induced and age-related developmental aging. Chlorophyll degradation during leaf senescence reveals the carotenoids, such as anthocyanin and xanthophylls and is the cause of autumn leaf color in deciduous trees. Leaf senescence has the important function of recycling nutrients, mostly nitrogen, to growing and storage organs of the plant. Therefore this is an incorrect option. 

Hence, the correct answer is option (A) "Juvenile".

The alkaloid from Colchicum autumnale of Liliaceae induces (A) Sterility (B) Dormancy (C) Cell Division (D) Polyploidy

Question:

The alkaloid from Colchicum autumnale of Liliaceae induces 

(A) Sterility 

(B) Dormancy 

(C) Cell Division 

(D) Polyploidy

Answer: option (D) Polyploidy

Explanation:

Colchicine is an alkaloid from the tree Colchicum autumnale (meadow saffron), used to induce polyploidy in plants. It prevents the microtubule formation during cell division, thus the chromosomes do not pull apart like they normally do. Due to which cell has double the number of chromosomes that it would normally have. 

Thus, the correct answer is option D.

 

Ploidy level of Nucellus, Endosperm, Polar nuclei, Megaspore mother cell, female gametophyte respectively are (A) 2n,3n,n,2n,n (B) 2n,3n,2n,n,n (C) n,2n,n,2n,n (D) 2n,3n,2n,2n,n

Question:

Ploidy level of Nucellus, Endosperm, Polar nuclei, Megaspore mother cell, female gametophyte respectively are 

(A) 2n,3n,n,2n,n 

(B) 2n,3n,2n,n,n 

(C) n,2n,n,2n,n 

(D) 2n,3n,2n,2n,n

Answer: Correct option (A)  2n,3n,n,2n,n 

Explanation:

• Nucellus, microspore mother cells (MMC), and megaspore mother cells are part of sporophyte so these are diploid cells and their ploidy is 2n. And female gametophytes are part of gametophyte and ploidy is n. 
• The endosperm constitutes an organism separate from the growing embryo. About 70% of angiosperm species have polyploid endosperm cells. These are typically triploid but can vary widely from diploid (2n) to 15n.
• Sperm released fuses with the two polar nuclei forming a triploid cell that develops into the endosperm.
• A megaspore mother cell is a diploid cell in which meiosis occurs, resulting in the production of four haploid megaspores.
• Hence, Ploidy level of Nucellus, endosperm, polar nuclei, Megaspore mother cell, female gametophyte respectively are 2n,3n,n,2n,n.
• So, the correct answer is '2n,3n,n,2n,n'.

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Define All Types Of Errors In Physics.

Question:

Define All Types Of Errors In Physics.

Explanation:

In Physics, an error is defined as the difference between the actual value and the calculated value of any physical quantity.

There are two types of errors in physics:

Random Errors

Random error occurs when repeated measurements of the quantity give different values under the same conditions. This error occurs due to some unknown reasons.

Systematic Errors

Systematic errors occur when all the measurements of physical quantities are affected equally and give consistent differences in the readings. The error may occur due to:

• Poor calibration of the instrument
• Zero error in measuring instrument
• Incorrect calibration on the measuring instruments