1 / 9

Biology 2B

Biology 2B. Sexual reproduction in animals. Reproduction in animals. Usually sexual Usually separate sexes – male and females Hermaphrodites can produce both male and female gametes Fertilisation may be external or internal

keahi
Download Presentation

Biology 2B

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Biology 2B Sexual reproduction in animals

  2. Reproduction in animals • Usually sexual • Usually separate sexes – male and females • Hermaphrodites can produce both male and female gametes • Fertilisation may be external or internal • Development of the embryo may be external (eggs) or internal (live birth) • Parents may provide care for offspring

  3. External fertilisation • Gametes meet outside the body • Offspring usually develop externally in eggs • Reproductive structures are generally simple – gonads and ducts to external opening or cloaca • Organisms need water in order for gametes to meet and fertilise • Loss of gametes is high so large numbers must be produced

  4. Internal fertilisation • Gametes meet inside the body • Offspring may develop externally in eggs or internally in the uterus • Reproductive structures are more complicated – males usually have copulatory organs and females a structure where fertilisation can take place • Organisms no longer need water in order for gametes to meet and fertilise • Loss of gametes is lower so fewer gametes can be produced (especially in females)

  5. External development • Gametes may meet outside or inside the body, but embryos develop externally in eggs • Female reproductive structures are generally simpler than in organisms with internal development • Loss of embryos is high so large numbers must be produced • Some organisms try and reduce loss of embryos by behaviours such as nest building, mouth brooding or pouch brooding

  6. Internal development • Gametes meet inside the body (internal fertilisation) • Offspring develop internally in the uterus (placental mammals) or uterus and pouch (marsupials) • Female reproductive structures are generally more complex • Females need to spend more of their energy on reproduction • Loss of embryos is lower so fewer offspring are produced at a time

  7. The human male reproductive system 1 = vas deferens 2 = seminal vesicles 3 = prostate gland 4 = bulbo-urethral gland 5 = epididymis 6 = testes 7 = scrotum 8 = penis 9 = pelvic bone 10 = bladder 11 = urethra

  8. The human female reproductive system 2a 1 = ovary 2 = uterine tube 2a = fimbriae 3 = uterus 3a = cervix 4 = vagina 5 = clitoris 5a = prepuce of clitoris 6 = labia major 7 = labia minor 8 = pelvic bone 9 = bladder 10 = anus 11 = perineum

  9. Parental care Parental care varies from • None – parents leave the eggs to hatch by themselves • Limited – 1 or both parents guard the eggs until hatched • Extensive – offspring are raised until capable of fending for themselves Extensive care may be provided by • One parent • Both parents • A family group or herd Parental care requires more resources from the parents, but has a lower mortality rate in the offspring Generally, the greater the parental care, the fewer offspring are produced at a time

More Related