List of top Biology Questions

The endomembrane system includes endoplasmic reticulum $(ER)$, Golgi complex, lysosomes and vacuoles Mitochondria, chloroplast and peroxisomes are not the part of endomembrane system because their functions are not coordinated with the same

The chromoplasts contain fat soluble carotenoid pigments like carotene and xanthophylls etc These pigments give yellow, orange or red colour to some parts of the plant

The alternate type of phyllotaxy is the arrangement of leaves in which a single leaf arises at each node in alternate manner. The alternate type of phyllotaxy is seen in China rose and mustard plant.

The alimentary canal of the frog is short Frogs are carnivores

Test cross is the cross between the $F_1$ progeny and either of the parent types. Back cross is the cross between $F_1$ progeny and the double recessive genotype.

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.

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

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

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.

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.

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.

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