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.
THE FACTS. The normal resting heart rate for an adult ranges from 60 to 100 beats per minute. But some researchers believe it may be time to re-examine whatâs considered normal.Researchers have found that a resting pulse at the upper end of ânormalâ may indicate a higher risk of stroke and heart disease.HE FACTS. The normal resting heart rate for an adult ranges from 60 to 100 beats per minute. But some researchers believe it may be time to re-examine whatâs considered normal.