Biology Questions

Smooth Endoplasmic Reticulumdoes not contain ribosomes on its surface for which it is regarded as smooth. So, proteins cannotbe synthesised by SER provided protein synthesis is the primary task of ribosomes.

Parvovirus B19 causes severe anemia because it preferentially infects erythrocyte precursors.

a. Parvovirus B19 binds preferentially to the erythrocyte blood group P antigen on erythroid precursor cells.

Answers B, C, D are incorrect:

b. after entry the single-stranded viral DNA genome is transported to the cell nucleus where the host DNA polymerase synthesizes the complimentary DNA strand.

c. Parvovirus B19 infection can be diagnosed by direct detection of viral DNA not RNA.

d. the fetus of a seropositive mother is protected from infection by maternal circulating antibodies.

Plants are producers, which means they make their own food. Chloroplasts are organelles found in eukaryotic and plant cells that conduct photosynthesis. Chloroplasts absorb sunlight and use it in conjunction with water and carbon dioxide gas to produce food for the plant.

Plants use energy from sunlight to help make their food, but they need chloroplasts to do it.

Hence, in plants, chloroplasts are necessary for Photosynthesis.

We know that the circulatory system of our body is a loop. The Heart is the pump, the arteries and their smaller branches (arterioles) carry oxygen rich blood all through your body tissues from the heart and the veins and their smaller branches (venules) carry oxygen depleted blood and waste products back to the heart from all the body parts.

The given statement "All bones stop growing by the end of adolescence" is a FALSE statement.

Appetite is the desire to eat food, sometimes due to hunger. Appetite is triggered by environmental cues such as the smell or taste of food. Appealing foods can stimulate appetite even when hunger is absent.

The left atrium is the upper left chamber of the heart that receives blood from the pulmonary veins.

The heart is responsible for circulating blood throughout the body. The heart is divided into four chambers. The upper chamber is known as the atrium while the lower chamber is referred to as the ventricle.

In animals, parthenogenesis means development of an embryo from an unfertilized egg cell. In plants parthenogenesis is a component process of apomixis.Apogamy is a type of reproduction, occurring in some ferns, in which the sporophytedevelops from the gametophyte without fusion of gametes.Adventitious embryony also called sporophytic budding, is a type of apomixis in which an embryo develops directly from nucellus or integument tissue.So, all three are correct.