Biology (Part-VII) (Railway)

• Females always pass an X chromosome onto their off-spring.

• Only men have the Y chromosome. So, children inherit Y chromosome from their father.

• The best strategy to avoid acquiring HIV is to sex to a single known healthy person. Even barrier methods like condoms can ensure safe sex without the risk of acquiring HIV.

• It helps cells to develop turgor pressure, the pressure of the cell contents against the cell wall.

• Thus, it helps plants to with-stand the pressure of incoming water.

• The glomerulus and convoluted tubules are located in the kidney cortex, while collecting ducts are located in the pyramids of the medulla.

• HIV is not an untouchable disease. It does not spread at all through hugging, shaking hands, saliva, sweat or urine.

• HIV can be transmitted through direct contact with breast milk, vaginal fluid, semen and blood.

• This process is mainly directed by the difference in pressure of concentration.

• Hence, the gases move from a highly concentrated region to a region of low concentration.

• Bone cells are embedded in a hard matrix that is composed of calcium and phosphorus compounds.

• These compounds are responsible for the hardness of the bone tissue.

• There are three types of plastids, which are the chloroplast, chromoplast and leucoplast.

• Chloroplasts synthesize green coloured pigments and chromoplast produce pigments of different colours.

• Leucoplasts are involved in the storage of compounds like starch, proteins or fats.

• The endosperm inside the seeds helps in the growth and development of the embryo.

• It has starch as stored nutrition which allows the rapid growth of embryo.

• This whole process is called seed germination.

• They are excreted by the kidneys in the urine along with the other types of protein waste products.

• Urea is the major nitrogenous waste product, making up some 80% of it.