Year 9 Biology

What is the basic unit of life in multicellular organisms?

Cells

How many different types of specialized cells are in the human body?

Over 200

What do cells require for their functions?

Delivery and removal of gases, nutrients, vitamins, minerals, wastes, pH balance, and water.

What is the purpose of communication between cells in multicellular organisms?

To gain requirements and move substances throughout the body.

What are the levels of organization in multicellular organisms?

Cells, tissues, organs, and organ systems.

What is the role of sense organs?

To detect stimuli in the environment.

Name the five senses.

Sight, hearing, touch, taste, and smell.

What are stimuli?

Environmental conditions that the body must respond to, such as light, sound, touch, taste, and smell.

What are receptors?

Specialized cells in sense organs that detect and respond to specific stimuli.

What is the function of thermoreceptors?

To detect variations in temperature.

Where are thermoreceptors located?

In the brain (hypothalamus), spinal cord, abdomen, and skin.

What do mechanoreceptors detect?

Touch, pressure, sound, motion, and muscle movement.

Where can mechanoreceptors be found?

In the skin, skeletal muscle, and inner ear.

What is the role of chemoreceptors?

To detect changes in chemicals such as odours, foods/drinks, pH, and gases in the blood.

Where are chemoreceptors located?

In the nose, tongue (taste buds), brain, and heart.

What do photoreceptors detect?

Changes in light and color.

Where are photoreceptors found?

In the eyes.

What is the function of pain receptors (nociceptors)?

To detect intense stimuli and chemicals indicating danger, injury, or disease.

Where are pain receptors located?

Throughout the body, including skin, muscles, joints, and internal organs.

What is the function of the skin in terms of sense organs?

To contain receptors that detect touch and temperature.

How do chemoreceptors in the nose work?

They detect gaseous molecules dissolved in mucus, sending signals to the brain for smell interpretation.

What are taste buds and where are they located?

Taste buds contain chemoreceptors and are located within bumps called papillae on the tongue.

What are the two types of photoreceptors in the retina?

Rods (detect light intensity) and cones (detect color).

How does the ear detect sound?

Sound waves vibrate the eardrum, which is transmitted through ossicles to the cochlea, where mechanoreceptors send signals to the brain.

What is the main function of the human body systems?

To maintain coordinated balance and support the functions of cells.

What is the significance of the five senses?

They enable survival by allowing the body to detect and respond to changes in the environment.

What do tissues consist of?

Cells of the same kind grouped together.

What is the function of organs in multicellular organisms?

Carry out specialised roles within the organism.

What are organ systems?

Organs of different kinds working together to form specialised body systems.

What is an organism?

The total of all organ systems working together to maintain life.

How many body systems are there in humans?

11 body systems.

What is the main function of the digestive system?

Breaks down nutrients into a form that can be absorbed and used by cells.

What are sense organs?

Organs used to detect stimuli in the environment, including eyes, nose, ears, tongue, and skin.

What do thermoreceptors detect?

Variations in temperature of internal and external environments.

What do pain receptors (nociceptors) detect?

Intense stimuli and chemicals released by damaged or inflamed cells indicating danger, injury, or disease.

What is the role of the skin in the sense of touch?

Contains pain receptors and mechanoreceptors that detect sharpness and touch.

How does the nose contribute to the sense of smell?

Chemoreceptors detect gaseous molecules dissolved in mucus and send messages to the brain.

How do ears detect sound?

Mechanoreceptors in the inner ear detect vibrations caused by sound waves and send messages to the brain.

What is the function of the auditory nerve?

Transmits sound information from the inner ear to the brain for interpretation.

What are flowering plants also known as?

Angiosperms

What are the reproductive organs in flowering plants?

Flowers

What do flowers rely on to bring male and female gametes together?

Insects and other animals

What are the male gametes in flowering plants called?

Pollen

What part of the flower attracts birds and insects?

Petals

What is the function of the nectary in flowers?

To produce nectar

What protects the flower bud before it opens?

Sepal

What is the stalk that supports the anther called?

Filament

What is the male reproductive part of a flower called?

Stamen

What produces the female gamete in flowering plants?

Ovule

What is the sticky pad that pollen lands on?

Stigma

What connects the stigma to the ovary?

Style

What is the female reproductive part of a flower called?

Carpel or Pistil

What is pollination?

The transfer of pollen grains to the stigma

What is self-pollination?

When pollen is transferred from an anther to the stigma of the same plant

What is cross-pollination?

When pollen is obtained from a different plant of the same species

Why is cross-pollination beneficial?

It increases genetic variation among offspring

What type of flowers are usually insect-pollinated?

Flowers with attractive, brightly colored petals and nectaries

How do wind-pollinated flowers differ from insect-pollinated flowers?

They generally lack large scented petals or nectar and have anthers that hang outside the flower

What forms when pollen grains land on the stigma?

A pollen tube is formed

What is fertilization in flowering plants?

The joining of male and female gametes

What is the fertilized egg called?

Zygote

What surrounds the embryo in a developing seed?

Endosperm

What happens to the ovule after fertilization?

It becomes the seed

What does the ovary turn into during seed formation?

A fruit

What are the methods of seed dispersal?

By animals, water, wind, or by themselves

What is the purpose of reproduction in organisms?

Reproduction is essential for life on Earth to continue, allowing organisms to produce offspring for their species to survive for future generations.

What are the two main ways organisms reproduce?

Organisms reproduce either sexually or asexually.

What does asexual reproduction mean?

Asexual reproduction means 'without sex' and does not require the fusion of sex cells (gametes).

What are genetically identical offspring produced by asexual reproduction called?

Clones.

In which types of organisms does asexual reproduction mainly occur?

Asexual reproduction mainly occurs in single-celled organisms and some simple multicellular organisms.

What are the six main types of asexual reproduction?

The six main types are binary fission, budding, fragmentation/regeneration, spore formation, vegetative propagation, and parthenogenesis.

What is binary fission?

Binary fission is when an organism grows to a certain size and divides into two equally sized offspring, with identical genetic information.

Which organisms can undergo binary fission?

Binary fission can occur in both prokaryotes (such as bacteria) and eukaryotes (such as Amoeba, Euglena, and Paramecium).

What is budding?

Budding is a form of asexual reproduction where the offspring forms from an outgrowth of the parent, called a bud, which detaches to live independently.

In which organisms does budding predominantly occur?

Budding occurs predominantly in yeast and hydra.

What is fragmentation/regeneration?

Fragmentation is when the parent breaks into several pieces, each developing into a new adult, while regeneration refers to the ability to regrow lost parts.

Which organisms commonly exhibit fragmentation?

Fragmentation is commonly observed in flatworms and hydra, while regeneration can be seen in starfish.

What is spore formation?

Spore formation is a reproductive method where organisms like fungi and plants produce spores that contain genetic information to create clones.

What advantages do spores provide?

Spores provide an effective means of dispersing future generations and can survive adverse conditions until favorable conditions arise.

What is vegetative propagation?

Vegetative propagation involves using non-sexual parts of a plant (not flowers) to develop new individuals of the same type.

Give examples of structures used in vegetative propagation.

Examples include roots (sweet potato), bulbs (daffodils, onions), rhizomes (ginger), tubers (potatoes), runners (native violets), and cuttings (roses).

What is parthenogenesis?

Parthenogenesis is a process where females produce eggs that develop into embryos without fertilization, seen in bees, aphids, ants, and some lizards and sharks.

What are the success criteria for understanding asexual reproduction?

Success criteria include explaining the importance of reproduction, distinguishing between asexual and sexual reproduction, and describing various asexual reproduction methods.

What are three advantages of asexual reproduction?

Advantages include faster reproduction, no need for a mate, and the ability to produce many offspring quickly.

What are three disadvantages of asexual reproduction?

Disadvantages include lack of genetic variation, vulnerability to environmental changes, and potential for rapid population growth leading to resource depletion.

How do environmental conditions influence asexual reproduction?

Environmental conditions can determine whether asexual reproduction is beneficial or limiting, affecting survival and reproduction rates.

How can organisms reproduce asexually using examples?

Examples include binary fission in bacteria, budding in yeast, fragmentation in flatworms, spore formation in fungi, vegetative propagation in plants, and parthenogenesis in certain animals.

What is homeostasis?

The maintenance of a relatively stable internal environment within a narrow range.

What are the five key features of a stimulus-response model?

Stimulus, receptor, control centre, effector, and response.

What factors need to be kept within a certain range for homeostasis?

Temperature, pH, concentrations of ions (e.g., Na, K, Mg), glucose, water, oxygen, and carbon dioxide.

What systems are involved in the stimulus-response model?

The nervous system and the endocrine system.

What are stimuli?

Changes in the internal environment that need to be detected for homeostasis.

What are the types of receptors involved in detecting stimuli?

Photoreceptors, mechanoreceptors, chemoreceptors, thermoreceptors, osmoreceptors, and nociceptors.

What is the role of the control center in the stimulus-response model?

To process the stimulus and determine an appropriate response.

What are effectors?

Muscles or organs/glands that respond to messages from the control center.

What is negative feedback?

A counteractive response to a stimulus that returns the stimulus back to the normal range.

How does negative feedback function in temperature regulation?

If blood temperature is too high, the response is to lower it; if too low, the response is to increase it.

What is the nervous system's primary function in homeostasis?

To transmit electrical impulses to and from the central nervous system (CNS).

What are the three main types of neurons?

Sensory neurons, interneurons, and motor neurons.

What is the structure of a typical neuron?

It includes a cell body, dendrites, an axon, a myelin sheath, and axon terminals.