Biology - Online Test
Q1. The half of the total carbon dioxide fixation on earth is carried out by algae through
Answer : Option C
Explaination / Solution:
Being photosynthetic, algae increase the level of dissolved oxygen in their immediate environment.
Q2. Animal cell do not possess
Answer : Option D
Explaination / Solution:
Animal cell do not possess plasmodesmata but it contain ribosomes, centriole andplamalemma. Plasmodesmata is the connection between two plant cells.
Q3. _____ occurs in RNA instead of the nitrogenous base thymine found in DNA.
Answer : Option B
Explaination / Solution:
Uracil is one of the four nucleobases in the nucleic acid of RNA that are represented by the letters A, G, C and U. The others are adenine, cytosine, and guanine. In RNA, uracil binds to adenine via two hydrogen bonds.
Q4. Which of the following ecological pyramid is always erect and upright :
Answer : Option B
Explaination / Solution:
The pyramid of energy is always erect in both terrestrial and aquatic ecosystems. It is so because the energy accumulated by producers by photosynthesis is not stored in their body totally as some part of the energy they produce is used to perform different activities. So the energy flow decreases from producers to top level of consumer.
Q5. In Bacterial photosynthesis, hydrogen donar is
Answer : Option B
Explaination / Solution:
In green plants is the hydrogen donor and is oxidised to . Some organisms do not release during photosynthesis. When H2S, instead is the hydrogen donor for purple and green sulphur bacteria, the ‘oxidation’ product is sulphur or sulphate depending on the organism.
Q6. The exposure of carbon monoxide to animals
Answer : Option C
Explaination / Solution:
The toxicity in animals is caused by the extraordinary affinity of carbon monoxide for haemoglobin which is responsible for the oxygen transport (approx. 250 times greater affinity of carbon monoxide compared to oxygen.because of higher affinity it destroys the haemoglobin.
Q7. Polyploidy is induced through
Answer : Option B
Explaination / Solution:
Polyploidy is a condition in which multiple sets of chromosome is present in same cell in place of usual two sets (diploid). Cell division involves karyokinesis followed by cytokinesis. Colchicine prevents the cytokinesis that results the more than two sets of chromosome.
Q8. If all the members of a host species die then all its unique parasites also die off, representing:
Answer : Option C
Explaination / Solution:
Coextinction and cothreatened refer to the phenomena of the loss or decline of a host species resulting in the loss or endangerment of other species that depend on it, potentially leading to cascading effects across trophic levels.
Q9. Egg of reptiles and birds are
Answer : Option A
Explaination / Solution:
The eggs of reptiles and birds are polyecithal because they contain large amount of yolk inside the egg.
Q10. Outermost green leafy whorls of flower is called
Answer : Option B
Explaination / Solution:
The outermost whorl of flower is green leafy structure, called sepals. Sepals protect the flower in buds stage. It is generally attached with thalamus of the flower.
