Biology Trials

things i got wrong and need to review

vegetative propagation

a form of asexual reproduction in plants where new individuals are produced from vegetative parts such as stems, roots, or leaves.

asexual reproductive method for fungi - fragmentation

where peices of hyphae can separate and become new colonies

parthenogenesis

the development of unfertilised eggs into adults

advantage of parthenogenesis

is that it allows for rapid population growth without the need for male fertilization, enabling species to thrive in isolated environments.

disadvantage of parthenogenesis

is that it reduces genetic diversity, making the population more vulnerable to diseases and environmental changes.

Diploid definition

refers to a cell or organism that contains two complete sets of chromosomes, one from each parent, resulting in a total of (2n) chromosomes.

Haploid definition

refers to a cell or organism that contains a single set of unpaired chromosomes, resulting in a total of (n) chromosomes.

fertilisation definition

union of two haploid gametes to produce a diploid zygote

gamete definition

haploid sex cell (egg or sperm)

Gonad definition

the reproductive organ that produces gametes and hormones (e.g. ovary, testes)

hermaphrodite definition

an organism that has both male and female reproductive organs, allowing it to produce both sperm and eggs.

isogamete definition

gametes are identical

advantages for asexual reproduction

• allows the build-up of a large population in a short time

• does not require the need to find a mate

• energy is saved without the need to find a mate

• time is saved without the need to find a mate

• new areas can be rapidly colonised

• if features are suited to the environment and the environment is stable, genetic variation is not a priority and asexual reproduction is a quick way to produce the next generation

• if the organism is restricted to a particular area or environment without the means for male and female to meet, then asexual reproduction overcomes this problem

disadvantages for asexual reproduction

• all offspring are genetically identical to the parent and this is a problem for natural selection and evolution if the environment is changing

• variation is limited, which can make populations vulnerable to diseases and environmental changes.

• if a mutation limits survival ability then all offspring will have this harmful characteristic and have a limited life span

advantages for sexual reproduction

• offspring are similar to the parent but not identical and this provides variation for natural selection and evolution if the environment is changing

• variation (which is a favourable characteristic of a gene pool for a population to survive) can occur due to mutation, fertilisation with gametes from two parents and during meiosis with crossing over and random segregation

disadvantages for sexual reproduction

• requires time for the build up of a large population

• requires an individual to find a mate

• energy is used in the process of finding a mate

• time is required to find a mate

• time is required for new areas to be colonised

• if the environment is stable, genetic variation is not a priority for continuity of the species in the short term

• if the organism is restricted to a particular area or environment without the means for male and female to meet, then sexual reproduction becomes a problem

external fertilisation - how male gamete reaches female gamete

male gamete swims to female gamete

external fertilisation - copulation

no copulation

external fertilisation - number of gametes produced

high numbers of both male and female gametes produced

external fertilisation - chance of fertilisation and reason

low chance of fertilisation as male gametes are shed into a large space

external fertilisation - zygote development

zygote usually develops outside the bodies of male and female parents

external fertilisation - organisms involved

fish, amphibians, aquatic invertebrates, algae

internal fertilisation - how male gamete reaches female gamete

male gamete sims to female gamete

internal fertilisation - copulation

copulation occurs

internal fertilisation - number of gametes produced

high numbers of male gametes produced and fewer female gametes produced

internal fertilisation - chance of fertilisation and reason

high chance of fertilisation as male gametes are shed into a confined space

internal fertilisation - zygote development

zygote can be kept inside female’s body for development to provide protection

internal fertilisation - organisms involved

reptiles, birds, mammals, land plants

pollination definition

pollination is the transfer of pollen from an anther to the part of the seed that contains the ovule. This usually means pollen is transferred to the stigma. It can be cross-pollination or self-pollination and usually involves a pollinating agent (e.g. wind, mammal, water, insect, water)

parts of a flower

features that indicate a flowering plant is likely to be animal pollinated

are often colorful petals, strong scents, and nectar production to attract pollinators.

steps of pollination

1. Pollen maturation, 2. Pollen transfer to stigma, 3. Germination of pollen tube, 4. Fertilization of ovule.

main features of a prokaryotic cell (e.g. bacteria)

• cytoplasm

• cell wall

• cell membrane

• ribosomes

• nucleoid DNA

• plasmid

• flagellum

• fimbriae

• capsule

binary fission definition

binary fission is a type of cell division in which unicellular organisms reproduce asexually. Each daughter cell receives an identical copy of the genetic information.

outline the process of binary fission

The process of binary fission involves the replication of the organism's DNA, followed by the elongation of the cell, and finally the division of the cell into two identical daughter cells. It is a common method of asexual reproduction in prokaryotic organisms.

outline an advantage of binary fission as a means of ensuring the continuity of a species

binary fission produces two daughter cells identical to the parent. It is a form of asexual reproduction and is energy efficient (no energy is needed to find a mate) and can quickly produce many numbers. This is advantageous in favourable conditions.

outline a disadvantage of binary fission as a means of ensuring continuity of a species

For organisms reliant on binary fission genetic diversity occurs due to mutations. However, if the environment changes quickly and there has been little genetic change due to mutation, the small gene pool can lead to extinction of a particular species.

list the main features of protists

Protists are a diverse group of eukaryotic microorganisms, typically unicellular but some are multicellular. They can be autotrophic or heterotrophic, reproduce asexually or sexually, and often live in aquatic environments.

outline the main difference between binary fission and budding in protists

Binary fission produces two identical daughter cells, while budding involves a small outgrowth from the parent that develops into a new organism, leading to offspring that may differ in size and genetic makeup.

budding definition

Budding is a form of asexual reproduction in which a new organism develops from an outgrowth or bud on the parent, eventually detaching and becoming independent. This method allows for the generation of genetically similar offspring while maintaining the parent's structure.

Three examples of Australian organisms that use asexual reproduction to survive in their particular environment

are the jellyfish, hydra, and sponges. These organisms reproduce through methods such as budding, fragmentation, or fission, allowing them to thrive in diverse aquatic habitats.

spore formation definition

Spore formation is a reproductive process in which organisms produce spores, typically unicellular and capable of developing into a new individual. This method allows for survival in adverse conditions and the colonization of new environments.

where does fertilisation occur in the human body

in the oviduct

name some australian animals and explain how fertilisation is ensured

Some Australian animals include frogs, birds, and marsupials. Fertilization is ensured through various strategies such as external fertilization in frogs, where eggs are fertilized in water, and internal fertilization in birds and marsupials, where fertilization occurs within the female's body.

Explain why reproductive adaptations are needed in Australia

Reproductive adaptations are needed for survival in Australia as many areas have harsh conditions and mating and fertilisation need to be timed to minimise the effects of the environment. Producing offspring at favourable times increases the chances of continuity of the species.

These adaptations may include changes in mating behaviors, timing of reproduction, and the development of specialized reproductive structures to ensure successful fertilization and rearing of young.

define each structure of the male reproductive system

The male reproductive system consists of several structures including the testes, which produce sperm and hormones; the epididymis, where sperm matures; the vas deferens, which transports sperm; the seminal vesicles and prostate gland, which contribute to seminal fluid; and the penis, which delivers sperm during mating.

define each structure of the female reproductive system

The female reproductive system consists of several structures including the ovaries, which produce eggs and hormones; the fallopian tubes, where fertilization occurs; the uterus, where a fertilized egg implants and develops; and the vagina, which serves as a passageway for sperm and childbirth.

androgens definition

Androgens are steroid hormones that stimulate the development and maintenance of the male reproductive system and secondary sexual characteristics

(e.g. testosterone is an androgen)

identify each part of a mammalian seminiferous tubule

A mammalian seminiferous tubule consists of several key parts including the germinal epithelium, which contains spermatogonia, Sertoli cells that support and nourish developing sperm cells, and the lumen where mature sperm cells are released.

identify the parts of a mammalian ovary and the stages of development of follicle and corpus luteum

A mammalian ovary includes structures such as the ovarian cortex, which contains follicles at various stages of development; the ovarian medulla, which houses blood vessels and nerves; and the corpus luteum, formed after ovulation. The stages of follicle development include primordial, primary, secondary, and tertiary follicles, concluding with the formation of the corpus luteum following ovulation.

implantation definition

implantation is the attachment of a developing embryo to the endometrium of the uterus at the start of pregnancy

Distinguish between fertilisation and implantation

Fertilisation is the union of two haploid gametes to produce a diploid zygote (fertilised egg) whereas implantation is the attachment of a developing embryo to the endometrium of the uterus at the start of pregnancy.

What produces hormones and how do they travel to the rest of the body?

Hormones are produced by glands in the endocrine system, such as the pituitary, thyroid, and adrenal glands. They travel to the rest of the body through the bloodstream, binding to specific receptors on target cells to elicit responses.

What controls the release of luteinising hormone and follicle stimulating hormone in both sexes?

The release of luteinising hormone (LH) and follicle stimulating hormone (FSH) is controlled by the hypothalamus through the secretion of gonadotropin-releasing hormone (GnRH), which stimulates the anterior pituitary gland to produce these hormones.

what happens in negative feedback?

in negative feedback a change that is being monitored causes a response that counteracts the initial response

Follicle Stimulating Hormone (FSH) - source

the anterior pituitary gland, stimulated by GnRH from the hypothalamus.

Follicle Stimulating Hormone (FSH) - target organ

the ovaries in females and the testes in males.

Follicle Stimulating Hormone (FSH) - function

To stimulate ovarian follicle development and estrogen production in females, and spermatogenesis in males.

Luteinising Hormone (LH) - source

the anterior pituitary gland, regulated by GnRH from the hypothalamus.

Luteinising Hormone (LH) - target organ

the ovaries in females and the testes in males.

Luteinising Hormone (LH) - function

To initiate ovulation in females and then convert ruptured follicle into corpus luteum, and stimulate interstitial cells to produce testosterone in males.

Oestrogen - source

ovary - follicular cells and then corpus luteum

Oestrogen - target organ

endometrium of uterus, whole body

Oestrogen - function

to regulate the menstrual cycle, promote secondary sexual characteristics, and trigger the development of the endometrium for implantation.

Progesterone - source

corpus luteum in the ovary

Progesterone - target organ

endometrium of uterus

Progesterone - function

to maintain the endometrium for pregnancy, maintain pregnancy, and inhibit ovulation.

Testosterone - source

testes - interstitial cells

Testosterone - target organ

whole body

Testosterone - function

maintaining secondary sexual characteristics of males

distinguish between the menstrual cycle and the ovarian cycle

The menstrual cycle (also known as the uterine cycle) refers to the changes that occur in the uterus and involves oestrogen secreted by the growing follicle causing the endometrium to thicken. Oestrogens and progesterone levels from the corpus luteum develop and maintain the lining of the endometrium and when the hormone levels drop, the endometrium disintegrates and a menstrual flow begins.

The ovarian cycle refers to the events that occur in the ovary. The ovarian cycle begins with the release of GnRH from the hypothalamus which stimulates the pituitary gland to release LH and FSA. A follice develops in the ovary in the follicular phase, the follicle ruptures during ovulation, releasing an oocyte. In the luteal phase, the ruptured follicle becomes the corpus luteum, which secretes hormones to support potential pregnancy.

ovarian cycle

What changes in the ovarian and menstrual cycles would you expect if there is fertilisation?

If fertilisation occurs, implantation follows and human chorionic gonadotrophin is released by the embryo which maintains the corpus luteum and prevents it degenerating. The corpus luteum continues to produce oestrogen and progesterone to maintain the endometrium until the placenta develops and takes over this role (about 2 months). Other features include low FSH and LH levels, rising oestrogen and progesterone levels and no menstruation.

conception definition

conception is the process of becoming pregnant with the union of viable sperm and ovum at the optimal time in the ovarian cycle

describe the process of an ova implanting into the uterine wall

1. ruptured follicle has released the egg and it will develop into the corpus luteum

2. fertilisation in the fallopian tube

3. blastocyst embryonic stage

4. implantation of blastocyst in uterine wall

blastocyst definition

A blastocyst is an embryonic mass of cells that forms after about 5 days and consists of a ball of cells around an inner cavity. It implants in the endometrium of the uterine wall. Implantation causes the endometrium to be maintained and stops the next menstrual flow.

How does the ova move down to the fallopian tubes?

The ova moves down the fallopian tubes via ciliary action and muscular contractions of the tube walls.

what are the germ layers?

The germ layers are three primary layers of cells formed during embryonic development: the ectoderm, mesoderm, and endoderm. These layers give rise to various tissues and organs in the body.

steps in development of triploblastic animals

zygote → cleavage and mitotic division → morula → blastula → gastrula (with three germ layers)

tissues and organs arising from ectoderm layer

The ectoderm layer gives rise to the epidermis, nervous system, and sensory organs, including skin, hair, nails, and the neural tube.

tissues and organs arising from mesoderm layer

The mesoderm layer gives rise to structures such as muscles, bones, the circulatory system, and various internal organs, including the kidneys and heart.

tissues and organs arising from the endoderm layer

The endoderm layer gives rise to the digestive tract, respiratory system, and glands such as the liver and pancreas.

embryo definition for humans

The early stage of human development, formed from the fertilized egg, which eventually develops into a fetus.

foetus definition for humans

A developing human after the embryonic stage, typically from the end of the eighth week of pregnancy until birth.

outline the three main stages of labour

1. dilation of the cervix to form the birth canal

2. expulsion with the bursting of the amniotic membrane, the gush of amniotic fluid and birth of the foetus

3. expulsion of the placenta and membranes (afterbirth)

outline the function of Human Chorionic Gonadotrophin (hGH) during pregnancy

Human Chorionic Gonadotrophin (hCG) is a hormone produced by the placenta shortly after implantation. Its primary function is to maintain the corpus luteum, which in turn supports progesterone production, essential for the continuation of pregnancy.

outline the function of oestrogen during pregnancy

Oestrogen helps maintain pregnancy by stimulating uterine growth, enhancing blood flow, and regulating other pregnancy hormones.

outline the function of progesterone during pregnancy

Progesterone is a hormone produced mainly by the corpus luteum and later by the placenta. It plays a crucial role in maintaining the uterine lining, preventing contractions, and supporting early fetal development.

function of each hormone during labour and birth

labour is regulated by hormones. Oxytocin is released from the posterior pituitary gland and stimulates uterine and breast smooth muscle contractions. There is positive feedback to release more oxytocin and prostaglandins, that are regulators to maintain uterine contractions until birth occurs.

monotreme definition

egg-laying mammal with hair, produces milk and no nipples

marsupial definition

young born immature and complete development in pouch connected to nipple

Placental definition

Young born at an advanced state. Have a placenta that connects the blood supply of the mother and offspring

What was the Neolithic Revolution?

The Neolithic Revolution was the first agricultural revolution that occurred around 10,000 years ago with the growing of crops and agriculture, and the domestication of animals.

what is the cell cycle

The cell cycle is the series of stages that a cell goes through to grow and divide, including interphase and the mitotic phase, resulting in two daughter cells.