more questions

what is the total number of chromosomes in a typical body cell of a person with down's syndrome

47. the normal number is 46. down syndrome results from the presence of an extra chromosome.( meiotic nondisjunction)

a plant cell with 12 chromosomes undergoes normal mitosis. what is the total number of chromosomes in each of the resulting daughter cells?

12. chromosomes are structures in the nucleus. during mitosis, two cells with identical chromoses are formes.

in human males, sperm cells are suspended in a fluid medium. the main advantage gained from this adaptation is that the fluid

acts as a transport medium for sperm. this fluid is known as semen, its primary function is to provide a protective watery medium for sperm cells as they enter the female reproductive tract.

in a particular area, living organisms and the nonliving environment function together as

an ecosystem.

an organism that makes its own food without the direct need for any light energy is known as a

chemosynthetic autotroph. produces its own food without the use of light energy. it obtains the energy from certain chemical reaction that take place in the cell

of the following, the greatest amount of the earths food production is thought to occur in

coastal ocean waters.

an environmental change that would most likely increase the rate of photosynthesis in a bean plant would be an increase in the

concentration of carbon dioxide in the air. the greater the concentration of carbon dioxide, the greater the rate of photosynthesis.

animals cannot synthesize nutrients from inorganic raw materials. therefore, animals obtain their nutrients by

consuming performed organic compounds. carbohydrates, lipids and proteins are the organic nutrients needed by all organisms.

most of the minerals within an ecosystem are recycled and returned to the environment by the direct activities of organisms known as

decomposers. Release minerals from decaying plant and animal bodies and return them to the environment.

by what process does carbon dioxide pass through the stomates into the leaf

diffusion.

if the first stage of an uninterrupted human menstrual cycle is the follicle stage, the last stage includes the

shedding of the uterine lining.the menstrual cycle is a series of changes that occur within the female reproductive system. the events of the cycle prepare the uterus to recieve an embryo. the lining of the uterus is built up.

in a developing embryo, the mesodern layer normally gives rise to

skeletal tissue. each of the germ layers of the embryo is responsible for the development of the systems of the body. the skeletal system develops from the mesoderm. the muscle system, circulatory system, and excretory system also evolve from the mesoderm.

in humans, a single primary sex cell may produce four gametes. these gametes are known as

sperm cells. primary sex cells give rise to gametes. gametes are formed by the process of meiosis. in meosis a diploid cell divides twice to form four monoploid cells.

in human females, the main function of the follicle stimulating hormone(FSH) secreted by the pituitary gland is to

stimulate activity in ovaries. follicles contain immature egg cells. the follicles are found in the ovary.

asexual reproduction differs from sexual reproduction in that, in asexual reproduction

new organisms are genetically identical to the parent.asexual reproduction invloves the mitotic process.

which is an important adaptation for reproduction among land animals?

fertilization of gametes within the body of the female.

in sexual reproduction, the 2n chromosome number is restored as a direct result of

fertilization.

which occurs in a plant cell but not in an animal cell during mitotic cell division?

formation of a cell plate. mitosis is the process by which two identical nuclei are formes. mitotic cell division is usually followed by cytoplasmic division. the cell plate is composed of membrane fragments from the endoplasmic reticulum.

which organism carry out heterotrophic nutrition

fungi. they are nonfreen plants. they are heterotrophs which means that they cannot manufacture their own food.

in most mukticellular animals, meiotic cell division occurs in specialized organs known as

gonads. they are sex glands, that are produced from primary sex cells that undergo meiosis. male gonads are testes, and female gonads are ovaries.

which statement best describes internal fertilization?

it helps to make terrestrial life possible.internal fertilization occurs within the body of the parent. the conditions in the female reproductive tract provide an ideal environment for the survival and pairing of gametes, helping to ensure that fertilization occurs successfully.

what is the function of the placenta in a mammal?

it permits the passage of nutrients and oxygen from the mother to the fetus. the placenta is an area f spongy tissue in the uterus. it is very rich in blood vessels. the placenta functions as a respiratory and excretory organ of the fetus.

which energy conversion occurs in the process of photosynthesis

light energy is converted to chemical bond energy. in the process of photosynthesis, carbon dioxide and water molecules are converted to glucose. light is the energy source for the reaction.

which world biome has the greatest number of organisms

marine.a biome is a large area dominated by one major type of vegetation and one type of climate.

what are the normal chromosome numbers of a sperm,egg and zygote, respectively?

monoploid, monoploid, diploid. sperm cells and egg cells are monoploid(n) gametes formed during the process of meiotic cell division.