development. The third part is ovaries which produce eggs to be fertilized. During intercourse the vagina is usually lubricated by a secretion from Bartholin’s glands. Eggs released in the ovaries reach the uterus via fallopian tubes. Production of gametes‚ gametogenesis‚ takes place in specialized tissues known as gonads. It occurs when cells in the tissue undergo meiosis. This process results in the division of the normal cells containing 46 chromosomes into cells containing 23 chromosomes. In males
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Normal cell division meiosis and gamete production via meiosis. Explain why the process of mitosis and meiosis are both important to a living organism. When would an organism need to undergo the process of mitosis? Meiosis? What would happen if meiosis did not occur? Mitosis is the cell process of growth and division whereas meiosis is the process of developing reproductive cells. The sperm and egg are critical components for almost all living organisms. Every living organism begins with one
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Germ Line Control of female Sex Determination in Zebrafish In order to identify the sex of a developing embryo‚ many scientists have studied this process called sex determination that allows them to have better understandings on how sex is being determined in either vertebrates or invertebrates. Sex determination is normally determined genetically; however‚ other factors can contribute to its determination. There are numerous determinants that control sex determination‚ but the most important are
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INTRODUCTION Parthenogenesis is a form of asexual reproduction in which growth and development of embryos occur without fertilization. In animals‚ parthenogenesis means development of an embryo from an unfertilized egg cell and is a component process of apomixis. The word parthenogenesis comes from the Greek‚ parthenos‚ meaning "virgin" and genesis‚ meaning "birth".[1] The term is sometimes used inaccurately to describe reproduction modes in hermaphroditic species that can reproduce by themselves
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Cell Cycle Definition- The process of the cell to divide into new cells. Interphase Description- the phase that occurs before cell division‚ the preparation for cell divisions Stages: G1- Rapid growth of the cell‚ metabolic activity. S- Synthesis‚ DNA replication. G2- Getting ready for cell division. Centrioles replicate Mitosis and Cell Division Function- To grow repair and maintain the cells in the body along with the reproduction of those cells. Results- Two identical daughter
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Genetics Review DNA (Deoxyribonucleic Acid): Stored inside chromosomes and contain all instructions for life It is made up of Ribose (sugar)‚ phosphate‚ and when of 4 Nitrogenous bases (Adenine‚ Thymine‚ Guanine and Cytosine) A Nucleotide consists of a Phosphate molecule‚ a sugar molecule‚ and a Nitrogenous base pair The nitrogenous bases always pair up AT and CG Each human has 46 chromosomes 23 pairs in total 1 pair sex chromosomes (that define your sex‚ male XX‚ female XY) 22
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daughter cells. They each have the same exact number and kind of chromosomes as the parent cell. Meiosis occurs in the primary sex cells leading to the formation of viable egg and sperm cells. They reduce the number of chromosomes to half in each gamete so that when they are getting furtilized‚ the species chromosome number is kept even. Mitosis happens in the reproduction of unicellular organisms and in the addition of cells to a tissue or organ in a multicellular organism. There are four stages
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Fertilization –introduction Amphibians accomplish fertilization of their eggs in a variety of ways. External fertilization‚ employed by most frogs and toads‚ involves a male holding a female in a pose called amplexus. In amplexus‚ the male releases sperm over the female’s eggs as they are laid. Less risky is the method employed by many salamanders whereby the male deposits a packet of sperm called a spermatophore onto the ground. The female then pulls it into her cloaca where fertilization occurs
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Centre Number For Examiner’s Use Candidate Number Surname Other Names Examiner’s Initials Candidate Signature Question General Certificate of Secondary Education Higher Tier January 2014 Mark 1 2 3 Additional Science M (modular) MBL2HP 4 Unit Biology B2 5 H Biology M (modular) Unit Biology B2 Wednesday 8 January 2014 9.00 am to 10.00 am 6 7 TOTAL For this paper you must have: a ruler. You may use a calculator. B Time allowed 1 hour Instructions Use black ink or black ball-point
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Re 7B Reproduction About the Unit This Unit covers human reproduction and development. The Unit starts with an overview of what reproduction is and considers different modes of reproduction in animals. Human reproductive organs are then covered‚ along with adaptations of sex cells. This is followed by a look at sexual intercourse‚ the menstrual cycle‚ pregnancy and birth. The Unit ends with puberty and adolescence‚ a stage which many pupils will be going through or just about to
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