cones are specialized reproductive structures of the sporophyte. Each cone consists of several âscalesâ arranged around an axis. Each scale is a sporophyll that will bear the spores of the sporophyte generation. An ovulate cone has many hard, radiating scales, each bearing a pair of ovules. Pollen cones are generally much smaller than ovulate cones; they contain many sporangia, each of which makes numerous haploid spores by meiosis. Male gametophytes (pollen grains) develop from the spores.
Bradycardia was defined as a heart rate less than 60 beats per minute when textbooks asserted that the normal range for heart rates was 60â100 BPM. The normal range has since been revised in textbooks to 50â90 BPM for a human at total rest.
A normal resting heart rate is usually 60-100 beats per minute. Your number may vary. Children tend to have higher resting heart rates than adults. The maximum heart rate is, on average, the highest your pulse can get. To calculate your predicted maximum heart rate, use this formula: 220 - Your Age = Predicted Maximum Heart Rate. For example, a 40-year-old's predicted maximum heart rate is about 180 beats per minute. Your actual maximum heart rate can be determined by a graded exercise test.