CBSE 12TH BIOLOGY - Online Test
Q1. The endosperm cells in angiosperms are
Answer : Option D
Explaination / Solution:
Endosperm is the product of triple fission in which two polar nuclei fuse with one of the male gamete. Endosperm provide nutrient to the developing embryo
Q2. Which should be considered more realistic growth model
Answer : Option B
Explaination / Solution:
Verhulst-Pearl logistic model of growth is more realistic growth model in comparison to exponential model of growth. Population growing in a habitat having limited resources shows sigmoid curve like growth before reaching to carrying capacity.
Q3. Cancer cells are damaged by radiations while others are not because cancer cells are
Answer : Option B
Explaination / Solution:
Cancer cells are killed by radiation to treat cancer. Cancer cells are undergoing rapid division and radiation killed these cells but normal cells are not affected by these radiation therapy.
Q4. All the terminator codons begin with the nucleotide of
Answer : Option A
Explaination / Solution:
Terminator codon do code for any amino acids. UAA, UAG, UGA are three codon that do not code for amino acids. All three terminator or stop codon start with U.
Q5. Breeding crops with higher levels of vitamins and minerals or higher protein and healthier fats is called
Answer : Option D
Explaination / Solution:
Bio-fortification is the breeding of crops with higher levels of vitamins and minerals to improve public health. Nutritional quantity is increased for protein, vitamins and minerals.
Q6. Select the group which represents only critically endangered species (as per 2008 red list):
Answer : Option B
Explaination / Solution:
According to red data book 2008, Critically endangered is the highest conservation status animals. The Amur Leopard who has just over 60 individuals left in its population. The Cross River Gorillas are a population between 200 and 300 individuals. Hawksbill Turtle, Leatherback Turtle have all unknown population numbers.
Q7. The actual covering of testis is a dense, bluish white fibrous connective tissue sheath called
Answer : Option C
Explaination / Solution:
The covering of testis is a bluish white fibrous tissue sheath called tunica albuginea. Tunica albuginea also projects inside testis to form a thick incomplete vertical column called mediastinum.
Q8. Inheritance of skin colour in humans is an example of
Answer : Option C
Explaination / Solution:
Skin colour in human being is an example of polygenic inheritance. Eight different genes are involved in deciding the skin colour ranging between white to black.
Q9. Which of the following organisms not fix atmospheric nitrogen
Answer : Option C
Explaination / Solution:
Spirogyra is a filamentous alga. This alga does not fix atmospheric nitrogen. Anabaena, Nostoc and Oscillatoria can heterocyst that can fix atmospheric nitrogen.
Q10. Spraying of DDT produces pollution of
Answer : Option C
Explaination / Solution:
Spraying of DDT produces pollution of air, water and soil. DDT is used as pesticides in agricultural field. It is non-biodegradable and reach to water bodies to pollute it. Some DDT also remains present in air as mist.
