biology module 5 notes complete - year 2020 new syllabus PDF

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complete biology notes for module 5, year 2020 graduate, 95 final hsc mark....

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Reproduction- the biological process that helps give rise or birth to new organisms from their parents. 1- Asexual reproduction- includes only one parent and gives rise to offspring that are genetically identical to each other. Advantages Quick No mate Requires less energy

Disadvantages Genetically identical No variation Easily wiped out Overcrowding Competition

PlantsVegetative propagation- where new individuals arise from portions of root, stem, leaves or buds of adult species.  Runners- long thin modified stems that grow along the surface of soil. Eg. Strawberry.

 Rhizomes- underground modified stems which give rise to a new shoot at each node. Eg. Grass and ferns.

 Suckers- modified roots which give rise to new plants. They can also sprout from buds near the base of parent plant. Eg. Apple trees.

 Tubers- swollen underground stems with buds that grow into new plants. Eg. Potatoes.

Animals Budding- adult organism gives rise to a small bud, which separates from the parent and grows into a new individual. Eg. Yeast, jellyfish, sponges.  Binary fission (splitting into 2)- Main mode of reproduction in unicellular organisms such as bacteria and protists. A newly divided cell grows to twice its size, replicates its DNA, and splits into two cells with identical genetic material.

 Spores- unicellular reproductive cells produced by fungi. They are easily dispersed, and expand the distribution of the species, enabling them to colonise new environments. Eg. Moulds and mushrooms.  Regeneration- detached part of an individual grows into another individual. Eg. Sea star.  Parthenogenesis- development of unfertilised eggs into adults. Does not require finding a mat. Eg. Honey bees. 2- Sexual reproduction- includes two parents who produce offspring that contain a mixture of the parents’ genes and therefore differ from each other and from their parents. Advantages Unique offspring- genetic variation Suited to new and changing environments Not easily wiped out -

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Disadvantages Requires energy Time consuming Mate needed Competition To prevent the chromosome number from doubling in each successive generation, each parent only contributes half of their chromosomes. This is possible due to the process of meiosis. Meiosis produces gametes which are haploid (one set of chromosomes). Sperm (n) + egg (n)  zygote (2n)  embryo.

Fertilisation can be internal or external. It is the fusion of sperm with the egg.

External fertilisation-

The union of gametes outside the body. Restricted to aquatic environments (or moist). Lower chance of fertilisation. Needs production of many gametes. Chances of fertilisation are increased by synchronisation of reproductive cycle. Exposure to light change, pH, and predators. Advantages include wide dispersal of young which reduces competition for food and space, no expenditure of energy, more offspring rapidly. Examples: staghorn coral, bony fish.

Internal fertilisation-

The union of gametes inside female’s body. Terrestrial. Few eggs needed, embryo protected and there is parental care of offspring, increasing chances of survival. Higher chance of fertilisation in confined space. Examples: reptiles and birds (internal fertilisation, external development) & mammals (internal fertilisation and development). Disadvantages include energy requirement, need for a mate and time consuming. Parental care is also lengthy and leaves female vulnerable. External fertilisation

Internal fertilisation

Male gametes swim to female gametes

Male gametes swim to female gametes

No copulation

Copulation occurs

Male gametes shed into large space; less chance of fertilisation Many female gametes produced

Male gametes shed into confined space; greater chance of fertilisation Few female gametes produced

Zygotes develop outside male and female partners Most common in fish, amphibians and algae

Zygote can be retained inside the female’s body for protection until fully developed Most common in land plants, reptiles, birds and mammals

PlantsPollination: the transfer of male gamete (pollen grain) to the female gametes (ova).  Pollen from the anthers lands on the stigma; a pollen tube germinates and grows down the style, causing the fusion of pollen grains with the ova. The fertilised ovule develops, protected by the ovary into a seed, while the ovary becomes the fruit.  Cross-pollination is when pollen from anther of one plant is transferred to stigma of another plant. Self-pollination is transfer of pollen from anther to stigma of same flower or another flower on same plant. Seed dispersal:  Prevents overcrowding and competition for light, water and soil nutrients.  Increases the chances of continuity of species in sudden environmental changes.

Germination:  The embryo inside a seed is in a dehydrated form and is dormant to allow the seed to survive adverse conditions.  If the seed lands in suitable soil, it germinates, producing a radicle (absorbs water and minerals), as well as a plumule (for photosynthesis).

Analyse the features of fertilisation, implantation and hormonal control of pregnancy and birth in mammals. Sexual reproduction in mammals Internal fertilisation, embryo implantation and pregnancy maximise reproductive success.  Reduced number of young are produced; internal development and parental care increase chances of survival.  Hormones are chemicals secreted by the different glands which coordinate many aspects of functioning. Eg. Pituitary gland being master gland regulating other endocrine glands. Sex hormones They specifically affect the growth and functioning of the reproductive organs or the development of secondary sexual characteristics.  Produced in ovaries, testes, pituitary gland and adrenal cortex.  Female in ‘oestrous.’ Types of sex hormones1- Androgens (males) such as testosterone that control the development and functioning of male sex organs and secondary sexual characteristics. 2- Oestrogens: control the development and functioning of the female reproductive organs and secondary sexual characteristics. Responsible for onset oestrous in females. Also plays a role in maturation of sperm. 3- Progesterone plays a primary role in pregnancy and stimulates the secretion of milk in mammary glands in 3rd trimester. Structures of the male reproductive system-

 Testis- production of sperm and testosterone.  Epididymis- where sperm matures and develops the ability to swim. It is stored here.  Vas Deferens- long tube conducts sperm form testes to prostate gland (which connects to urethra).  Seminal vesicle- secretes fluid containing fructose (nourish sperm), mucus (protects) and prostaglandin.  Prostate gland- secretes alkaline fluid to neutralise vaginal acids.  Urethra- conducts sperm/ semen from prostate gland outside the body via penis. Structures of the female reproductive system-

 Ovary- where oocytes mature prior to release (ovulation)- responsible for progesterone and estrogen secretion.  Fimbria- tissue adjacent to an ovary sweep oocyte into oviduct.  Oviduct- transports oocyte to uterus, also where fertilisation takes place.  Uterus- where fertilised egg implants.  Endometrium- lining of uterus which thickens in preparation for implantation or otherwise lost via menstruation.  Vagina- passage leading to uterus by which penis can enter (protected by cervix).

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Spermatogenesis depends on testosterone secreted by Leydig cells. The pituitary secretes:  Follicle stimulating hormone (FSH)- stimulates maturation of follicles in the ovaries.  Luteinising hormone (LH)- promotes ovulation and development of corpus luteum.  Prolactin- acts on breast tissue in preparation for and maintain milk production.

The ovarian cycle- The pituitary gland is controlled by the hypothalamus (& GnRH) 1- Follicular phase: Primary follicle  Graafian follicle  LH produced  ovulation (GF bursts) 2- Ovulation 3- Luteinising phase: Lasts 14 days, begins after ovulation. The burst follicle enlarges to become corpus luteum, secretes progesterone to prepare uterus for pregnancy. Corpus luteum breaks into corpus albicans if no fertilisation takes place.

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Corona radiata is first thing sperm has to go through. It is the protective layer of an egg. Zona pellucida regulates binding of sperm to egg. Cortical granules prevent polyspermy.

When asked about fertilisation, you must talk about the cortical and acrosomal reactions!!!  Acrosomal reaction(enables sperm to fuse with egg nucleus) Sperm approaches the zona pellucida of the egg. Hydrolytic enzymes are released which digest the jelly coat, making a pathway through the zona pellucida so that sperm can fuse with the plasma membrane. Sperm nucleus is engulfed.  Cortical reactionThe zona pellucida hardens to form a block to polyspermy (correct number of chromosomes maintained).

The menstrual cycle Starts with menses. Endometrium breaks down and accompanied by bleeding (menstruation).  New endometrium lining forming.  Corpus luteum secretes progesterone and some oestrogen. Progesterone acts on uterus for implantation.  If pregnancy occurs, uterus lining is maintained by progesterone and oestrogen. Later it is produced by the placenta. The placenta secretes progesterone, oestrogen and HCG. Corpus luteum begins to degenerate.

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An embryo secretes HCG:  Acts like LH, maintaining corpus luteum.  Produces oestrogen and progesterone.  Stimulates growth of placenta and uterine enlargement.  Inhibits menstruation. By 2nd trimester, HCG declines, corpus luteum degenerates, placenta produces progesterone and oestrogen. LH stimulates the production of testosterone. FSH stimulates the production of a protein by Sertoli cells that maintain high enough testosterone to form sperm. Hormone inhibin reduces the levels of FSH.

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When sperm make contact with zona pellucida, glycoprotein binds to recognition molecules of the head of the sperm, triggering acrosomal reaction.

Positive feedback response- response causes more of the stimulus. For example, oxytocin released during labour allows the baby’s head to put pressure on the uterus. This causes contractions. Receptors signal for more oxytocin to be produced as a result. Negative feedback response- response counteracts initial stimulus. For example, when body temperature rises, body sweats. The role of the placenta: -

Hormones; oestrogen, progesterone, HCG Exchange of blood It takes the role of corpus luteum Progesterone prevents contractions From mother; glucose, water, oxygen, minerals From baby; urea, water, carbon dioxide, HCG Placental villi (structure) increases surface area for diffusion/ exchange of blood (function)

Birth (parturition) The process is stimulated by the rise in estrogen (estriol). It increases the responsiveness of the uterus walls to oxytocin. Estriol also inhibits progesterone, which was preventing uterine contractions.  Oxytocin stimulates contractions and opening of the cervix.  The foetus responds to contractions by releasing prostaglandins, which triggers further contractions.  Relaxin softens the cervix.  Progesterone and oestrogen decrease during labour.  Oxytocin expels the placenta.  Prolactin causes enlargement of mammary glands and stimulates lactation.

Evaluate the impact of scientific knowledge on the manipulation of plant and animal reproduction in agriculture. -

Agriculture is the cultivation and breeding of animals, plants and fungi. Scientific knowledge that has been applied to reproductive technologies in agriculture:  Hormones of reproduction  Genetic inheritance  Multiple ovulation and embryo transfer  Sex determination (manipulation of gametes XY)

Reproductive techniques:  -

Selective breeding Selective breeding is the choosing of two plants/animals with desirable qualities and breeding them in order to produce offspring with desirable qualities (hybrid vigour). In the past, only characteristics in the gene pool were able to be used but now there is knowledge and skills to use cloning and transgenic technologies to transfer genes from one species to another.

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Advantages include larger, more nutritious or aesthetically pleasing products, high yields, greater resistance to disease/pest and more palatability. Disadvantages include that unwanted traits may also pass as genes are carried on the same chromosome (linked genes), reduced biodiversity, outcompetes other species. Example- Bt cotton is genetically modified cotton. Before, they were sprayed with pesticides. Gene inserted from bacteria allows it to make its own pesticide. Farmers are allowed to save money and non-targeted species are not affected.

EVALUATE- state and define the technique, describe/state the scientific knowledges used, advantages, disadvantages, example, judgement statement.

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Artificial insemination Artificial insemination is the injection of sperm cells of a male into the reproductive tract of the female without any sexual contact. Knowledge: gametes have genetic information, hormones of reproduction. Advantages: reduces the harm of mating process or injuries obtained from transportation, increases possible number of offspring. Disadvantages: high cost of specialised equipment, time consuming, potential of injury to female, reduction in biodiversity. Example: good beef bull.

There is artificial pollination too, which is the same process but it involved removing pollen grains from the stamens of a flower and dusting them on to the stigma of another.  -

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Animal and plant cloning Cloning is the process of creating a genetically identical organism using a somatic cell from another mature organism. Knowledge: genetic inheritance and how genetic material is found in the nucleus. There is also an understanding of meiosis, mitosis and the elements of sexual and asexual reproduction. For animals, somatic cell nucleic transfer technology is used whereas for plants it is tissue culture. Tissue culture- a plant is cut into tiny pieces and placed into a growth medium. Advantages- high yield, disease resistant and aesthetically plants and animals. It enables desired traits to be reproduced in a short space of time and allows favourable characteristics to be maintained. Disadvantages- all genetically identical, genetic diversity is greatly reduced. Also, it makes the population susceptible to being wiped out in the occurrence of a disease or the change in environmental conditions. Example- cow with good milk, rose bush stem cut and placed in the ground. Cell replication How important is it for genetic material to be replicated exactly?

Cell replication- the form of cell division in which a parent cell divides to produce two daughter cells. In eukaryotes, it is through mitosis. -

Restores nucleus to cytoplasm ratio Growth and development Maintenance and repair

The cell cycle -

Involves growth, replication of DNA and division to produce two identical daughter cells. 3 main phases: interphase (chromosome replicates & takes most time), mitosis (nucleus divides) and cytokinesis (cytoplasm divides).

G1, G2, S  interphase

G1- first growth phase: organelles and proteins are replicated. The cell increases in size. S- synthesis phase; DNA replicated in nucleus. G2- second growth phase; the cell continues to increase in size and DNA replicated is checked for errors. Mitosiso o o

Growth Repair and replacement Asexual reproduction

It is a process during cell division in which the cell nucleus divides in two. It ensures that daughter calls receive the same number and type of chromosomes as the parent cell. 12345-

Prophase Metaphase Anaphase Telophase Cytokinesis

Prophaseo o o

Chromosomes condense and become visible Spindle fibres emerge from centrosomes Nuclear envelope breaks down

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Nucleolus disappears

Metaphaseo o

Chromosomes are lines up at metaphase plate (equator) Each sister chromatid is attached to spindle fibre from opposite poles

Anaphaseo

Sister chromatids (now chromosomes) are pulled towards opposite poles

Telophaseo o o

Chromosomes arrive at opposite poles and begin to decondense Nuclear envelope surrounds each set of chromosomes Spindle breaks down

Cytokinesiso o -

Plant cell- cell plate separates daughter cells Animal cell- cleavage furrow separates daughter cells Is the division of the cytoplasm following the division of the nucleus Stabilises internal concentration of materials in the two new cells Ensures each cell carries one nucleus to carry out functions

In mitosis, daughter cells have same 2n number of chromosomes as parent. In meiosis, 2n becomes n as it is a reduction division. This ensures chromosome numbers remain the same for generations. Sources of variation1234-

Mutations Crossing over Independent assortment Random fertilisation

Crossing over can occur when homologous chromosomes line up side by side (Prophase I) and sections of inner chromatids break and swap positions. The point of crossover is called chiasma. This leads to an exchange of genetic material between maternal and paternal chromosomes and therefore increases genetic variation as new combinations of alleles on the same chromosome are produced.

Random segregation/ independent assortment can bring about variation. This is whereby homologous chromosomes line up randomly along the cell equator i.e maternal and paternal chromosomes do not line up on the same side of the equator. Homologous chromosomes then separate and move to the opposite poles of a cell in a random manner, creating different gene combinations on different chromosomes. Each cell has new combinations of alleles compared to those in the parent cell. Genetic variation increases the chance that some organisms will survive under adverse conditions.

Advantages of meiosis to a species:  

Meiosis forms gametes with half the number of chromosomes so that after fertilisation, the offspring formed will have the correct number of chromosomes. Crossing over and random segregation during meiosis produces genetic variation and it is the variation that allows natural selection to occur and thus allows evolution over time.

The first division of meiosis Prophase I- Cell has 2n chromosomes: n is haploid number of chromosomes. - Homologous chromosomes pair (synapsis) - Crossing over occurs (allele, variations!) Metaphase I- Spindle microtubules move homologous pairs to the equator of the cell. - Orientation of maternal and paternal chromosomes is random (independent assortment) Anaphase I- Homologous pairs are separated. One chromosome of each pair moves to each pole.

Telophase I- Chromosomes uncoil. During interphase that follows, no replication occurs. - Reduction of chromosome number from diploid to haploid completed. - Cytokinesis occurs. Second division of meiosis Prophase II- Chromosomes, which still consist of two chromatids, condense and become visible. - Spindle apparatus forms at right angles to previous spindle. - Nuclear envelope starts to break. Metaphase II- Sister chromatids line up at the equator and attach to spindle fibres.

Anaphase II- Centromeres separate and chromatids are moved to opposite poles.

Telophase II- Chromatids reach opposite poles. - Nuclear envelope forms. - Cytokinesis occurs.

A nucleotide1. Sugar molecule 2. Phosphate group 3. Nitrogenous base

DNA replication using the Watson and Crick DNA model, including nucleotide comp...