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Reproduction Flashcards iGCSE Biology

Reproduction Flashcards iGCSE Biology

iGCSE Biology Flashcards – All Topics

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[h] Reproduction Flashcards iGCSE Biology

[q] Advantages of Breast-Feeding

[a]

  • Provides balanced nutrients / food;
  • Easy to digest;
  • Provides passive immunity against pathogens;
  • Sterile;
  • Is at correct body temperature;
  • Bonding with mother;
  • No additives;
  • No preparation;
  • No cost;
  • Provides, best / complete / most suitable / AW, food;
  • Easy to digest / less risk of colic;
  • No additives / less risk of allergies / child less likely to develop
  • Diabetes;
  • Contains antibodies / reference to colostrum / provides passive
  • Immunity / provides protection against,
  • Pathogens / diseases / microorganisms;
  • Sterile / less risk of infection;
  • Is at, body / correct, temperature;
  • No preparation / always available;
  • Bonding with mother;
  • It’s free / ‘cheap’;
 

[q] Advantages of sexual reproduction (in plants)?

[a]

  • Genetic variation / diversity;
    • ref to, alleles / genes / DNA, from different, plants / parents;
    • Allows mutations to be expressed / AW;
    • Allows adaptation to, new conditions / changed environment / AW;
    • (new species) can evolve / allows natural selection to occur;
    • pollen exchanged between individuals / cross pollination;
  • Seeds are dispersed;
    • Can colonise new areas / AW;
    • Less competition (with parent plant / among offspring);
  • Seeds may be dormant;
    • Survival through, harsh / adverse, conditions;
  • Allows, variation / genetic diversity;
  • Plant more likely to survive (named) environmental change;
  • Resistance to disease;
  • Ability to evolve;
  • ref. to fitness;
 

[q] Antenatal Care

[a]

  • Antenatal (before birth), care is the name given to the care and advice given to expectant mothers along with checks on fetal growth and development
  • Whilst pregnant, expectant mothers are given advice on:
    • Diet:
      • Iron: For red blood cells / haemoglobin / to transport oxygen / prevent anemia
      • Proteins: Growth and development of fetus
      • Calcium: Growth of bones and teeth of fetus
      • Folic Acid.
    • Exercise:
      • Stay fit
    • Health precautions:
      • Avoiding infections, tobacco, alcohol and other drugs
 

[q] Artificial insemination (AI)

[a]

PROCEDURE
  1. Doctor provides (named) fertility drug early in menstrual cycle; e.g. When follicle(s) are developing / 14 days before AI;
  2. Sperm is collected from male donor;
  3. Sperm is placed into uterus around the time of ovulation;
REASONS FOR USING AI
  • Male
    • Low sperm count
    • Sperm too weak to reach uterus/oviduct.
  • Female
    • Abnormal uterus wall.
    • Vagina too acidic
 
  1. Provide (named) fertility drug early in menstrual cycle; e.g. When follicle(s) are developing / 14 days before AI;
  2. Collect, sperm / semen (from male);
  3. Place, semen / sperm, into uterus / vagina / through cervix;
  4. Around the time of ovulation;
 

[q] What is Asexual reproduction?

[a] A process resulting in the production of genetically identical offspring from one parent is called Asexual reproduction.

 

[q] Asexual reproduction Advantages

[a]

  • Favourable / good characteristics of parent passed on;
    • Easier to adapt to same environment as parent;
  • Less energy / resources used;
    • No gametes;
  • Fast reproduction time;
  • Dense colonies outcompete other species;
  • Only one parent required;
 

[q] What is Cross-pollination?

[a] Transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species is called Cross-pollination.

 

[q] Cross-pollination Advantage

[a]

  • More variation.
    • Cross-pollination results in more genetic diversity in a species, thus the species can adaptand is more resilient to diseases. 
  • Less competition for offspring.
 
 

[q] Cross-pollination Disadvantage

[a]

  • Cross-pollination can only occur when the flowers are open.
  • Less chance of pollination.
 

[q] Describe how the ancestors of the great white shark developed adaptive features such as good eyesight

[a]

  • 1.   Variation (in eyesight);
  • 2.   Ref. To mutation;
  • 3.   New alleles arise that increases fitness;
  • 4.   (organisms with better eyesight) are better competitors;
  • 5.   Organisms with the good eyesight / feature, are more likely to survive and reproduce; ora
  • 6.   Passing on their alleles (for good eyesight);
  • 7.   Eventually all the organisms (in the population) will have the
  • 8.   Feature / good eyesight;
  • 9.   Ref to natural selection / evolution;
 

[q] Describe the role of stem cells in the growth of an embryo? 

[a]

  • Ref. to unspecialised cells;
  • That can become specialised;
  • Ref. to expression of genes in specialised cells;
  • AVP ; e.g. continually divide.
 

[q] What is a Development?

[a] Increase in complexity is called Development.

  • Increase in complexity;
  • (Named) cells / tissue(s) / organ(s) / organ system(s), become specialised / differentiate / AW;
 

[q] Disadvantages of Breast-Feeding

[a]

  • Time consuming;
  • Transfer of HIV or Alcohol;
  • Painful;
  • Stressful / may be embarrassing;
  • Mother may not be able to produce enough milk;
  • Cannot see how much baby has consumed;
  • Task cannot be shared with other parent;
  • Time consuming;
  • Transfer of, viruses / HIV / Hepatitis B ;
  • Painful / sore nipples / mastitis;
  • Stressful / may be embarrassing / AW;
  • Mother may not be able to produce enough milk;
  • Cannot see how much baby has consumed;
  • Task cannot be shared with other parent;
  • Medications / drugs / alcohol, can pass to baby;
 

[q] Environmental problems caused by non-biodegradable plastics in streams and rivers.

[a]

  • Plastic cannot decompose;
    • Visual pollution;
  • Destruction of habitat / ecosystem / food chain;
    • Ingested plastic cannot be digested;
    • Plastic Suffocate and choke organisms;
    • Plastic blocks light for photosynthesis;
      • Reduces concentration of (dissolved) oxygen ;
  • May release toxins / harmful chemicals;
    • Idea of bioaccumulation / biomagnification;
  • Blocks the flow of water in streams or rivers;
  • Plastic cannot decompose;
  • Ingested plastic cannot be digested;
  • Plastic trapped and strangle organisms AW;
  • Plastic blocks light for, photosynthesis;
  • May release toxins / harmful chemicals;
  • Blocks the flow of water in streams or rivers;
  • Reduces concentration of (dissolved) oxygen ;
  • Destruction of habitat / ecosystem / food chain;
  • Idea of bioaccumulation / biomagnification;
  • Visual pollution
 

[q] Explain the importance of meiosis in sexual reproduction

[a]

  • Chromosome number halved / becomes haploid;
  • Genetic / DNA variation;
  • New combinations of alleles;
  • Fertilisation restores diploid number in zygote / ensures number of chromosomes remains constant in next generation;
 

[q] Features of Male Gametes

[a]

 

[q] Female reproductive structures and their function:

[a]

  • Ovary:
    • Contains follicles which develop into the ova.
    • Produces progesterone and oestrogen
  • Oviduct:
    • Carries an ovum to the uterus, with propulsion provided by tiny cilia in the wall; 
    • Site of fertilisation.
  • Uterus:
    • Where the fetus develops
  • Cervix:
    • A ring of muscle, moist by mucus with a small opening, separating the vagina from the uterus
  • Vagina:
    • Moist tube of muscle, flexible and secretes mucus
    • Receives penis and sperm during intercourse, and way out for baby at birth.
 

[q] Female Secondary Sexual Characteristics

[a]

  • Oestrogen produced.
  • Hips broaden.
  • Start of ovulation and menstruation.
  • Breast size grows.
  • Growth of pubic hair.
  • Size of uterus and vagina grow.
 

[q] What is Fertilisation?

[a] The fusion of gamete nuclei is called Fertilisation.

 

[q] Fertilisation Process

[a]

  1. Acrosome enzymes are released (from sperm);
  2. Acrosome enzymes break down / digest jelly coat of ova;
  3. Sperm head enters the ova;
  4. Haploid nuclei of sperm and ova fuse together to form a diploid zygote;
  5. Fertilisation membrane forms / jelly coat hardens, so that no more sperm can enter;
  6. Mitosis of zygote, forming a hollow ball of cells called a blastocyst;
    • Use of energy stores from egg cell (for mitosis)
  7. Blastocyst moves along the oviduct towards the uterus;
    • Ciliary movement / peristalsis, in the oviduct;
 
  • (acrosome) enzymes break down, jelly layer / AW;
  • Sperm, head / nucleus, enters egg;
  • Fertilisation membrane forms / no more sperm can enter;
  • (haploid) nuclei, fuse / join;
  • (diploid) zygote formed;
  • Mitosis / cell division;
  • (2 / more – celled) embryo forms;
  • (hollow) ball of cells / embryo / zygote / fertilised egg, moves down the oviduct;
  • Ciliary movement / peristalsis, in the oviduct;
 

[q] Fertility Drugs

[a]

  • Drugs like Clomiphene are taken early in menstrual cycle;

Effects:

  • Inhibits action of oestrogen;
  • Stimulates release of FSH and LH;
      • Makes sure that FSH concentration is high enough;
  • To stimulate development of follicles
    • More eggs are released;
  • LH stimulates ovulation;
 
  • (Named) drug (e.g. FSH / clomiphene / clomid), injected / taken, early in menstrual cycle;
  • Inhibits action of oestrogen;
  • Stimulates, production / release, of FSH;
  • Makes sure that FSH concentration is high enough;
  • To stimulate production / development / maturation of, follicles / eggs / ova / oocytes;
  • More eggs are released;
  • LH stimulates, ovulation / release of eggs;
 

[q] How do bacteria reproduce asexually?

[a]

  • DNA replicates;
  • Cell membrane / cell wall develops in the middle of the cell;
  • Binary fission;
    • Bacteria divides into two;
 
  • DNA / chromosome / genetic material, replicates / is copied;
  • cell membrane / cell wall, develops in the middle of the cell;
  • binary fission;
  • bacteria / cell / cytoplasm, divides into two;
 

[q] In-Vitro Fertilisation (IVF)

[a]

PROCEDURE
 
  1. Woman given hormone treatment to stimulate egg production.
  2. Multiple eggs taken from ovary.
  3. In the lab, eggs are mixed with sperm in a culture petri dish to be fertilised.
  4. Fertilised eggs placed in an incubator for 48 hours.
  5. Embryos are implanted in the uterus or frozen for future implanting.
REASON
 
  • Surgery cannot be used to repair
 

[q] Labour and Birth

[a]

  1. Contractions of the muscles in the uterus wall.
    • Labour starts
    • Regular rhytemic contractions become stronger and more frequent
    • Stimulation by [hormone] increases
      • Helped by [hormone] (more sensitive to [hormone])
      • Prevented by [hormone] (that decreases fully before birth)
  2. Breaking of Amnion.
    • Release amniotic fluid.
  3. Dilation of Cervix.
    • Gradually widens enough to let baby’s head pass through.
  4. Passage through Vagina.
    • Muscular contractions of uterus wall and abdomen push baby head-first through the cervix and vagina.
  5. Tying and cutting of the umbilical cord.
    • Baby can breathe on its own.
  6. Delivery of the afterbirth.
    • Placenta breaks away from uterus and pushed out seperately.
 

[q] Male reproductive structures and their function

[a]

  • Testes:
    • Have many coiled tubes which produce sperm, and the cells between tubes produce testosterone.
  • Scrotum:
    • A sac that holds the testes outside the body, keeping them cooler than body temperature
  • Sperm duct:
    • Muscular tube that links the testis to the urethra in order to allow the passage of semen containing sperm
  • Prostate gland:
    • Adds fluid and nutrients to sperm to form semen
  • Urethra:
    • Passes semen containing sperm through the penis;
    • Aso carries urine from the bladder
  • Penis:
    • Male sex organ
    • To insert into the vagina of the female during sexual intercourse in order to transfer sperm
 

[q] Male Secondary Sexual Characteristics

[a]

  • Testerone Produced
  • Voice deepen
  • Production of sperm
  • Maturation of penis and testes
  • Growth of pubic and facial hair
 

[q] Menstrual Cycle

[a]

  • Day 1-5
    • Follicle Stimulating Hormone (FSH) produced by pituary gland
      • Stimulates maturation of one follicle
        • Follicle secretes oestrogen
    • Endometrium breaks down (Menstruation)
  • Day 5-12
    • Oestrogen/Estradiol released by ovary
      • Causes repair and growth of endometrium (Thickening)
      • At high concetration, inhibits FSH
        • Stops maturation of follicle
        • Stimulates pituary gland to secrete Luteinising Hormone/Lutropin (LH)
  • Day 13-15
    • LH (secreted by pituary gland)
      • Causes Ovulation [Day 14] (release of ova from ovary)
        • Body tempertaure increases.
        • Formation of Corpus Luteum from ovulating follicle 
  • Day 15-28
    • Corpus Luteum
      • Secretes progesterone
    • Progesterone
      1. Stimulate endometrium to thicken and produce more blood vessels
      2. Prepare endometrium for implantation
      3. Inhibit LH (at high concentrations)
      4. Inhibit FSH (at high concentrations)
 

[q] Methods of Birth Control in Humans

[a]

  • Barrier
    • Condom
      • Thin rubber sheath covering over penis
      • Traps sperm, preventing them from reaching uterus
      • Protects against impregnation/STIs
    • Femidom
      • Rubber sheath with rings, one inserted into vagina and one outside
      • Sperm trapped, reduces STI chance
    • Diaphragm
      • Thin rubber disc placed in vagina, covering cervix.
      • Sperm trapped, but chance of STI
 

[q] Methods of Birth Control in Humans

[a]

  • Chemical
    • Intra-Uterine Device (IUD)
      • T-shaped plastic and copper device
      • Inserted into wall of uterus, preventing implantation
    • Intra-Uterine System (IUS)
      • T-shaped
      • Releases (synthethic) progesterone slowly over a long period of time in uterus to inhibit FSH.
    • Contraceptive Pill
      • Pill contain oestrogen and progesterone to prevent ovulation
    • Contraceptive Implant
      • Small plastic tube inserted under the skin of upper arm of a woman
      • Slowly release progesterone preventing pregnancy
    • Contraceptive Injection
      • Progesterone injected, thickening mucus in cervix and thins the endometrium
      • Sperm prevented in cervix/no implantation.
 

[q] Methods of Birth Control in Humans

[a]

  • Natural
    • Abstinence
      • Avoid sex completely.
    • Avoiding fertile period
      1. Body Temperature
        • During/after ovulation, temperature rise by about 0.5℃ .
        • Infertile 3 days before and 1 day after ovulation.
      2. Cervical mucus
        • Mucus becomes more fluid as ovulation approaches.
 

[q] Name the Blue Stars

[a]

 

[q] Name the Green Star

[a]

 

[q] Name the Green Stars

[a]

 

[q] Name the Green Stars

[a]

 

[q] Name the Purple Star

[a]

 

[q] Name the Yellow Star

[a]

 

[q] Name the Yellow Stars

[a]

 

[q] Name the Yellow Stars

[a]

 

[q] Name the Yellow Stars

[a]

 

[q] Name the Yellow Stars

 

[a]

 

[q] Name the Yellow Stars

[a]

 

[q] Outline how sewage should be treated before entering a stream

[a]

    1. Solids are filtered;
    2. Flocculation to separate suspended particles from water / sedimentation to settle particles in settling tank;
    3. Digestion by microorganisms in aeration tank;;
      • Any example ; e.g. Proteins → amino acids, starch → glucose, fat to fatty acids (and glycerol)
    4. Water is disinfected / chlorinated / treated with ozone / treated with UV;
    5. Distillation / collection of water from evaporator;
 
 
    • Remove solids / pass through a grid / filter / screening;
    • Allow to sediment / (primary) sedimentation / settling tank;
    • Use, microorganisms / bacteria / fungi ;
    • In aerobic conditions / oxygen supplied / aerobic digestion / aeration tank;
    • Microbes, digest / decompose, complex compounds to, simple / soluble, compounds;
    • Any example ; e.g. Proteins → amino acids, starch → glucose, fat to fatty acids (and glycerol)
    • Water is, disinfected / chlorinated / treated with ozone / treated with UV;
    • AVP ; e.g. Ref to respiration / recycling bacteria into aeration tank / flocculation described or explained
 
  • Filtration / screening to remove large pieces of waste;
  • Flocculation / coagulation to separate suspended particles from water / sedimentation to settle particles;
  • Digestion by, bacteria / fungi / decomposers / microorganisms;
  • With aeration (tank) / trickle filter / activated sludge;
  • Sludge treated with anaerobic decomposers / anaerobic digestion;
  • (water) treated with, chlorine / ozone / UV (light);
  • Distillation / collection of water from evaporator;
 

[q] Plant Fertilisation

[a]

  1. Pollen transferred to stigma
  2. The place where pollen grain absorbs liquid from the stigma develops to form a pollen tube.
    • This only happens if the pollen grain has landed on the same species of stigma 
  3. The pollen tube grows down the style.
    • Function of pollen tube: delivers male gamete downwards to ovule.
  4. The pollen tube enters ovule, in the ovary
  5. The tip of the pollen tube opens.
  6. Fertilisation occurs, male nucleus fuses with the female nucleus to form a diploid zygote
    • Each ovule in an ovary needs to be fertilised by a separate pollen grain.
  7. The zygote will start to divide by mitosis and forms an embryo, becoming the seed.
 

[q] What is Pollination?

[a] The transfer of pollen grains from the anther to the stigma is called Pollination.

 

[q] Pregnancy and development

[a]

  1. Zygote divides continuously to form a hollow ball of cells called a blastocyst;
  2. Blastocyst moves down the oviduct towards uterus;
    • By ciliary action / peristalsis / muscle contraction;
  3. Blastocyst implants / sinks into endometrium; 
  4. Growth and development of placenta occurs;
    • After 8 weeks, when all the organs are formed, the embryo is called a fetus. 
    • One of the first organs to form is the heart, which pumps blood around the body of the embryo.
  5. Follicle become corpus luteum;
  6. Corpus luteum secretes / releases progesterone ;
    • Progesterone maintains endometrium thickness
    • Progesterone prevents menstruation;
    • Inhibition of FSH (secretion / release);
      • Prevents, production of more eggs / production of follicles;
  • Forms a blastocyst / blastula
  • (hollow) ball / collection / group / AW, of cells;
  • Goes / moves, down oviduct / down fallopian tube / towards uterus;
  • Detail, e.g. Ciliary action / peristalsis / muscle contraction;
  • Implants / AW, into, lining of the uterus / endometrium / wall of uterus;
  • Growth / development, of placenta;
  • Follicle becomes, yellow body / corpus luteum / remains of follicle / AW;
  • Yellow body / corpus luteum / ovary / AW, secretes / releases / produces progesterone;
  • Progesterone maintains, endometrium / lining of uterus / wall of uterus / AW;
  • Progesterone, prevents menstruation;
  • Inhibition of FSH (secretion / release);
  • Prevents, production of more eggs / production of follicles;
 

[q] Pregnancy structures

[a]

Placenta

  • Villi begins to grow from embryo into endometrium soon after implantation
  • Function of Placenta:
    1. Gas Exchange
      • Transfer of dissolved nutrients, (e.g. glucose / amino acids / ions / water), from maternal (circulation) to fetal by diffusion;
      • Transfer of excretory products, (e.g. urea) from fetal circulation /to maternal by diffusion;
    2. Produce hormones
      • Progesterone (maintain thickness of endometrium) 
      • Oestrogen (prepare the mammary glands in the breasts for milk production)
    3. Passive immunity by antibodies from maternal to fetal.
    4. Prevent mixing of mothers blood and fetus blood
      • Mother’s blood pressure can damage fetus organs.
      • Different blood group between mother and fetus

Umbilical Cord

  • Physically attached to placenta and fetus
  • Function of Umbilical Cord:
    • Transport deoxygenated blood and metabolic waste from fetus to placenta.
    • Transport oxygenated blood and food substances from mother to fetus.

Amniotic Fluid/Amnion

  • Membrane that encloses the amniotic fluid
  • Function of Amnion :
    • Keep amniotic fluid from rupturing before birth.

Amniotic Fluid

  • Function of Amniotic Fluid
    • Protects fetus against mechanical shock.
    • Allow fetus to move to promote muscular development.
    • Prevent dehydration.
    • Act as lubricant before birth.
    • Maintain constant temperature
  • gas exchange / named example with direction;
  • transfer of (dissolved) nutrients, from maternal (circulation) / to fetal;
  • transfer of excretory products, from fetal / to maternal;
  • by diffusion;
  • produces / secretes, (named) hormone;
  • passive immunity / antibodies, from maternal / to fetal;
  • prevents / limits, mixing of blood;
  • ref to regulating blood pressure;
  • AVP;
  • e.g. maternal / fetal attachment point
  • e.g. ref to counter current flow / maintains concentration gradient
  • e.g. hormone function described
  • protection from (mechanical) shock (of fetus);
    maintains (constant) temperature (of fetus);
    allows movement (of fetus);
    prevents dehydration;
 

[q] What is Self-pollination?

[a] The transfer of pollen grains from the anther of a flower to the stigma of the same flower or different flower on the same plant is called Self-pollination.

 

[q] What is Sexual reproduction?

[a] A process involving the fusion of the nuclei of two gametes (sex cells) to form a zygote and the production of offspring that are genetically different from each other is called Sexual reproduction.

 

[q] Sexual Reproduction Disadvantage

[a]

  • Two parents required
  • Slower reproduction process
  • Requires more energy 
    • Because many eggs is wasteful
  • Offspring not be as well adapted to environment; 
 

[q] What is Sexually transmitted infection [STI]?

[a] An infection that is transmitted via body fluids through sexual contact is called Sexually transmitted infection [STI].

 

[q] Examples of Sexually Transmitted Infections (STIs)

[a] AIDS and HIV

  • AIDS: Acquired Immune Deficiency Syndrome
  • HIV: Human Immunodeficiency Virus
  • HIV causes AIDS.
    • HIV attacks lymphocytes, causing number of antibodies to decrease.
    • Body is vulnerable to minor diseases due to weak immune system.
 
 

[q] Sexually Transmitted Infections (STIs)

[a] TRANSMITTED BY

  • From mother to fetus / across the placenta;
  • From mother to baby at birth;
  • In breast milk;
  • Unprotected / unsafe sex;
  • Sharing needles / syringes;
  • In blood products / blood for transfusion / transplants / blood to blood contact;
 

[q] Sexually Transmitted Infections (STIs)

[a] Controlling Spread of STI

  • Use condom/femidom.
  • Successful treatment of HIV/AIDS by drugs
  • Education about HIV and AIDS
 

[q] Social implications of contraception and fertility treatments

[a] Contraception

    • Some religions prohibit it
 

[q] Social implications of contraception and fertility treatments

[a]

  • Artificial Insemination
    • Surrogate Motherhood/Anonymous donor
      • Children has identity crisis 
    • Religious/Moral Objections
 

[q] Social implications of contraception and fertility treatments

[a]

  • In-Vitro Fertilisation
    • Allows infertile couples/single parents/same sex couples to have children
    • Religious/Ethical concerns about IVF;
    • Expense of fertility treatment; 
    • May lead to multiple births; 
    • Idea of genetic screening before implanting is possible; 
    • Storage of, eggs/embryos, is possible (during chemotherapy); 
    • Has allowed stem cell research on embryos;
 

[q] Social implications of contraception and fertility treatments

[a]

  • Fertility Drugs
    • Idea that stress is associated with difficulty having children;
    • Stated problem with multiple births (e.g: Expensive to take care of multiple children)
    • Issues with elderly parent(s);
    • Religious objections to use of fertility drugs;
    • Treatment may be expensive;
    • Increases populations / any negative effect of population increase;
    • Can be used to increase populations / any positive effect of population increase; e.g. In countries with falling birth rates
 

[q] State the advantages of self-pollination 

[a]

  • Less wastage of pollen and energy by producing more pollens;
  • Greater chance of pollination;
  • No need for pollinating agents;
  • Does not require other plants of the same species to be nearby;
  • Offspring well adapted to environment of the parents;
 

[q] State the disadvantages of self-pollination

[a]

  • Less variation
    • Genotype become homozygous (over time).
    • Limited gene pool
  • Less chance of adapting to change in the environment;
    • More susceptible to disease;
  • May become extinct as a result
 

[q] State the features of Wind-pollinated plants

 

[a]

 

[q] Using hormones for contraception

[a]

  • Oestrogen
    • Encourages repair of endometrium after menstruation
    • Prevents release of FSH.
  • Progesterone
    • Maintains endometrium thickness
    • Inhibits secretion of LH.

[q] What are the advantages of seed dispersal? 

[a]

  • Colonise new areas ;
  • Reduce (intraspecific) competition ;
  • Reduce inbreeding ; ora

[q] What are the advantages of Sexual Reproduction on Animals? 

[a]

  • Maintain / increase population;
  • Allows variation;
    • (variation) caused by meiosis;
    • For example, through crossing over / independent assortment;
    • Random fusion of gametes;
    • Ability to express recessive traits / AW;
  • Adaptation to new / changed environments;
  • (allows) natural selection / evolution / formation of new species;

[q] What are the advantages of variation between individuals? 

[a]

  • Allows adaptation to new environment;
    • E.g. ref to new disease / camouflage / escaping from (new) predators
  • Allows selection / evolution ;
    • Ref to reduces competition ;
    • Increases chances of survival of the species / reduces chance of extinction ;
  • AVP ; e.g. increase in gene pool

[q] What are the differences between sperm cell and egg cell? 

[a]

  • Flagellum / tail / streamlined;
  • Motile / swim / AW;
  • Smaller / reference to actual sizes;
  • Acrosome / enzymes in packet on head;
  • No food store;
  • Less cytoplasm;
  • Contains x or y (chromosome);

[q] What are the role of enzymes in seed germination? 

[a] Stored food reserves are broken down. For example, starch is broken down by amylase into maltose which is used for energy.

  • Stored food / food reserves (in seed) broken down;
  • named enzyme plus substrate;
  • product plus use;
  • enzymes required in process of respiration;

[q] What happens during ovulation? 

[a]

  • release of an, egg / ovum / oocyte;
  • from, follicle / ovary;
  • into, oviduct / fallopian tube;

[q] Why shouldn’t pregnant women smoke?

[a]

  • Toxins / AW, in smoke can cross the placenta;
    • increased risk, of miscarriage / still birth / premature birth / low birth weight / deformities;
    • reduces oxygen available to the foetus / foetal brain damage;
    • increased risk, of reduced lung, function / infection, in foetus / infants;
    • babies more likely to become addicted / have withdrawal symptoms;
    • AVP;
 
 

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