I did buu whats the question?
They provide the immune system with "memory" against previously encountered pathogens.
T memory cells are necessary for protective immunity against invading pathogens
These are the factors that determine a nation's human development index (HDI):
1. Average life and health expectancy
2. Education- literacy rates, and ratio of students who are enrolled in primary, secondary and tertiary levels
3. Individual income- a person’s income against the gross domestic product (GDP)
Answer:
With the heavy inner core, the earth's orbit and rotation will remain stable over the long term, giving us day and night and summer and winter. ... These swirling convection currents result in the earth's magnetic field which keeps us properly oriented for travel, and shields earth from deadly cosmic rays
Explanation:
The inner core is the fourth layer inside the Earth. It is a solid metallic ball made mainly of iron. Here, temperatures reach extraordinary levels, estimated to be between 7,200–8,500ºF (4,000–4,700ºC). Although the inner core is very hot, it is not liquid like the outer core.
Answer: A. scalp hairs grow constantly throughout life.
Explanation:
Hair is a squamous keratinized epithelium which is consist of multi-layered flat cells. Hair are made up of protein called "keratin".
The statement "scalp hairs grow constantly throughout life" is false because at a particular age or due to several factors scalp hairs stop growing.
Scalp hair growth rate depends on three main factors including sex (female hair grows faster than male), age (hair growth slows with age), and ethnicity (Asian hair grows slower than Caucasian hair).
Scalp hair growth stops because of follicle devitalization when the hair length become two or three feet.
Hence, the correct answer is A. "scalp hairs grow constantly throughout life".
