CBSE 12TH BIOLOGY - Online Test
Q1. Introduction of sex education in schools should be encouraged to
Answer : Option C
Explaination / Solution:
Sex education in schools should be encouraged to provide right information to young and to discourage children from believing in myths and misconceptions about sex related aspects.
Q2. Disease or infections which are transmitted through sexual intercourse are collectively called
Answer : Option B
Explaination / Solution:
Venereal Diseases (VD) also referred to as Sexually transmitted infections (STI) and sexually transmitted diseases (STD) are infections that are commonly spread by sex, especially vaginal intercourse, anal sex or oral sex. Most STIs initially do not cause symptoms.
Q3. CAM is a special photosynthetic pathway found to be present as adaptation within:
Answer : Option C
Explaination / Solution:
Crassulacean acid metabolism photosynthesis pathway is present as adaptation in xerophytes in which stomata opens during night to prevents loss of water by transpiration.
Q4. The organism which causes pneumonia in human beings is
Answer : Option D
Explaination / Solution:
In human beings pneumonia is caused by bacterium Streptococcus pneumoniae that cause inflammation in lungs. This bacterium is atrichous as it lacks flagella of body surface.
Q5. _____ 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.
Q6. 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.
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. 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.
Q10. The endometrium in female is the lining of
Answer : Option C
Explaination / Solution:
The innermost lining of uterus is called endometrium. It is spongy layer that breakdown during menstrual cycle along with mucus through vagina.
