Hãy cho biết chu kì co bóp của tim?Xác định chu kì tim và lưu lượng oxi cung cấp cho tế bào người trong 6 phút ( biết rằng mỗi nhịp tim cung cấp cho tế bào 30ml oxi) V ận dụng các kiến thức sau - Ở người trưởng thành ( cơ thể khỏe mạnh bình thường), Mỗi chu kì co dãn của tim kéo dài 0,8 giây ( bao gồm pha: nhĩ co – 0,1s : pha thất co – 0,3s: pha dãn chung 0,4s) → Nếu thời gian của mỗi chu kì tim càng ít thì số nhịp tim trong mỗi phút ( 60s) càng cao và ngược lại - Tổng thời gian của 1 chu kì tim là 0,8s nên ta có công thức: t: khoảng thời gian tim hoạt động ( đơn vị s – giây )

the unequal cytoplasmic division that  results  in  one egg  and three polar bodies ensures that a fertilized  egg has  ample nutrients  forits journey  to  the uterus.

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!

answer: zinc is the substance which has a volume of 1.38 .

density is defined as the mass of an object per unit volume.

it can be calculated by dividing mass of a substance by its volume i.e.

si unit of density is kg per cubic meter and cgs unit of the same is gram per cubic centimeter.

now from the given data volume can be calculated by the formula .

hence, the volume of aluminium will be = which comes out to be 1.703 .

similarly, volume of zinc, chromium, and nickel will be 1.378 , 0.869 , and 0.356 respectively.

answer; coat color for blending in with dry grass;