All Free Biology MCQs with Answers

1231. Out of total organisms on earth, _____________are vascular plants?

• A. 53.10%
• B. 19.90%
• C. 17.60%
• D. 9.40%Preparing For College Admissions Tests

Explanation: Vascular plants are commonly given as about 17.6% of the total organisms in the classification used by this question. Students may choose 19.90% because it is a nearby percentage, but it does not match the stated biological classification statistic.

1232. A structure formed by groups of similar cells organized into loose sheetsor bundles performing similar functions is called as________?

• A. An organ
• B. An organism
• C. A Tissue
• D. A Cell

Explanation: A tissue is a group of similar cells arranged together to perform a common function, such as muscle tissue or epithelial tissue. An organ contains several different tissues working together, so students may choose organ if they confuse the levels of biological organization.

1233. Taking in liquid material into the cells is known as_________?

• A. Phagocytosis
• B. Pinocytosis
• C. Exocytosis
• D. Both a and b

Explanation: Pinocytosis is the form of endocytosis in which a cell membrane surrounds and takes in extracellular fluid and dissolved substances. Students commonly choose phagocytosis because both are forms of endocytosis, but phagocytosis takes in large solid particles rather than liquid.

1234. Amoeba can move with the help of?

• A. Flagella
• B. Pseudopodia
• C. Water
• D. Cilia

Explanation: Amoeba moves by extending temporary cytoplasmic projections called pseudopodia, or false feet, which also help it surround food. Students may choose cilia because cilia can produce movement in some unicellular organisms, but Amoeba has no cilia and moves by amoeboid movement.

1235. Study of insects is called_________?

• A. Immunology
• B. Parasitology
• C. Entomology
• D. Paleontology

Explanation: Entomology is the branch of biology concerned with insects, including their structure, classification, development, and behavior. Immunology studies immunity, parasitology studies parasites, and paleontology studies ancient life and fossils. The likely alternative is parasitology because many insects transmit parasites, but insect study itself is entomology.

1236. What is the branch of biology in which structure and function of tissues are studied___________?

• A. Cell Biology
• B. Taxonomy
• C. Histology
• D. Morphology

Explanation: Histology is the study of the microscopic structure and function of tissues, linking tissue organization with its biological role. Cell biology focuses mainly on cells, taxonomy classifies organisms, and morphology deals more generally with form and structure. Students most often choose morphology because it also concerns structure, but histology specifically concerns tissues.

1237. Which of the following hormone is predominantly responsible for bone weakening in older women?

• A. Progesterone.
• B. Oestrogen.
• C. Parathyroid hormone.
• D. Calcitonin.

Explanation: Oestrogen normally suppresses bone resorption and helps maintain bone mass; its decline after menopause allows osteoclast activity to exceed bone formation. Students may choose parathyroid hormone because it also promotes calcium release from bone, but the characteristic hormonal factor in older women is oestrogen deficiency.

1238. Normally, in the process of osmosis, the net flow of water molecules into or out of the cell depends upon differences in the ?

• A. Concentration of water molecules inside and outside the cell
• B. Concentration of enzymes on either side of the cell membrane
• C. Rate of molecular motion on either side of the cell membrane
• D. None of these

Explanation: Osmosis is the net movement of water across a selectively permeable membrane, driven by a difference in water concentration on the two sides. Option c is a likely distractor because temperature affects molecular motion, but the defining factor in osmosis is the water concentration gradient.

1239. About __________ of the body weight of a mammal is water ?

• A. 60%
• B. 65%
• C. 70%
• D. 75%

Explanation: Water commonly makes up about 70% of the body mass of a mammal, although the exact percentage varies with age, tissue type, and species. Students may choose 60% because it is a commonly quoted approximate value for some adults, but the standard textbook value here is 70%.

1240. Which Vitamin is needed for the formation of a light-sensitive pigment in the retina.

• A. Vitamin A
• B. Vitamin C
• C. Vitamin D
• D. B complex

Explanation: Vitamin A is converted into retinal, a component of rhodopsin, the light-sensitive pigment in rod cells of the retina. Students may choose a B-complex vitamin because several B vitamins support nervous-system function, but they do not form the visual pigment.