List of top Biology Questions

The acrocentric chromosome has centromere at the terminal position The metacentric chromosome has centromere slightly away from the middle of the chromosome

Stems of some plants protea them from browsing animals. Axillary buds of stems of these plants are modified into thorns.

Tendons attach one bone to another bone Ligaments attach skeletal muscles to bones

Sino-atrial node $(SAN)$ is called the pacemaker. $SAN$ generates the maximum number of action potentials and is responsible for initiating and maintaining the rhythmic contractions of the heart

Smooth muscles are known as involuntary muscles. Smooth muscles are controlled by autonomic nervous system

Sponges exhibit cellular level of organisation. In sponges, cells are arranged as loose cell aggregates.

Renal threshold of glucose is said to be $180 mg/100 mL$ Glucose starts appearing in the urine when its blood level exceeds $180 mg/100 \,mL$ of blood

Rudolf Virchow modified the hypothesis of cell theory given by Schleiden and Schwann Cell theory says that all cells arise from pre existing cells

Primary growth of the plants contributes to the elongation of the plants along their axis. Root apical meristem and shoot apical meristem are responsible for primary growth of the plants.

Photorespiration is a wasteful process. In photorespiratory pathway, there is no synthesis of sugars or$ ATP$.

Phloem fibres or bast fibres are made up of collenchymatous cells. Phloem fibres are generally found in primary pholem.

Phenotypic superiority of hybrid over either of its parents in one or more traits is termed hybrid vigour. Suppression of expression of recessive harmful genes occurs in heterozygotes.

Periodic abstinence is a method in which couples avoid from coitus from day $17$ to $27$ of menstrual cycle. Periodic abstinence is a very effective method and $100 \%$ sure of birth control.

Pancreas is a heterocrine gland Endocrine part secretes insulin and glucagon and exocrine part secretes an acidic pancreatic juice containing enzymes

Pairing and separation of pair of chromosomes would lead to segregation of a pair of factors they carried. Two alleles of a gene pair are located on similar sites on non-homologous chromosomes.

Oxytocin is called 'milk-ejection hormone'. Oxytocin acts on the smooth muscles of uterus and stimulates its contraction.

Osmosis is a special type of diffusion of water through a semi-permeable membrane. The net direction and rate of osmosis depends only on the pressure gradient.

Over-exploitation of a species reduces the size of its population eventually leading to its extinction. Steller's sea cow is a large, herbivorous, terrestrial mammal which is on the verge of extinction due to over exploitation.

Neurons protect and support the neuroglial cells Neuroglial cells make up ninety per cent neural tissue in our body

Nephrons are of two types : cortical and juxtamedullary according to their relative position in the cortex Juxtamedullary nephrons have short loop of Henle while cortical nephrons have long loop of Henle

Myelinated nerve fibres are present in spinal and cranial nerves Myelinated nerves conduct impulses more rapidly than unmyelinated nerves

n: The stage between the two meiotic divisions is called interkinesis. : Interkinesis is generally short lived.

Mycoplasmas are pathogenic in animals and plants. Mycopiasmas lack cell wall and can survive without oxygen.

Monoadelphous stamens are found in pea. In pea, stamens are united into one bunch or one bundle.

Metabolism refers to the sum of chemical reactions that occur within living organisms. Metabolic reactions occur simultaneously inside living organisms.