Biology Monthly Test

Monthly Test Notes

Movement in living things

Locomotion: The ability to move from place to place. (for example: walking)

Movement is a change in the position of a whole organism or parts of an organism.

Types of Movement

1. Growth movement - This type of movement happens as a plant grows. For example, plants grow upwards towards light, and roots grow downwards towards the ground due to gravity. (If a stimulus is applied from one direction, the response is usually in one

direction away from or toward the direction of the stimulus.)

1. Part movement - This movement is seen in parts of a plant or animal that don't move around much. For example: a plant’s leaves may close when touched or some plants’ petals open and close

- Sleep movement is the response to changes in light/temperature. Eg. Closing of petals of plants

- Feeding movement of plants. These plants have developed to trap and digest insects because they live in conditions with low nitrogen availability.

1. Locomotion - This is when an animal moves its entire body from one place to another. For example: animals like humans move by using the muscles that work with their bones to help them walk, run, or jump.

Why is it important for movement to occur in animals?

• Animals move around to find food. Plants make their food through photosynthesis, so their roots need to stay in the soil to take in water and minerals.

• Animals move to find a mate for reproduction. Plants depend on outside helpers, like insects and the wind, to spread their pollen for reproduction.

• Animals move to escape from predators. Some plants have developed ways to protect themselves from being eaten, like having spines or producing toxins that make them poisonous.

The importance of cartilage:

Cartilage - covers the ends of bones. It is smooth and acts as a shock absorber and stops the 2 bones from rubbing together.

The axial skeleton & The appendicular skeleton:

Functions of the skeleton

1. Locomotion

The ability to move from place to place

1. Support

Holds the body off the ground

Keeps it its shape even when muscles are contracting to produce movement

1. Movement

The skeleton works with muscles which are attached to it to produce movements and many bones of the skeleton act as levers.

1. Protection

• The brain is protected by the skull

• The vertebrae are protected by the spinal cord

• The ribs and breastbone (sternum) protect the lungs and heart

• The pelvis shields the reproductive organs

1. Production of blood cells

Red and white blood cells are made in the bone marrow.

Irritability in Plants (Tropisms)

Tropism - growth in response to stimulus

Irritability is the ability of a living organism to react to changes in its environment or stimulus.

Tropisms can either be negative or positive; negative tropism is growth away from a stimulus while positive tropism is growth towards a stimulus.

The role of Auxin

Plants respond to stimuli by producing a growth hormone called auxin which controls the direction of growth of roots or stems.

The most important plant tropisms are light, gravity and water.

Phototropism - responses to light

Geotropism - responses to gravity

Hydrotropism - response to water

Phototropism

This is the growth of the plant in response to light. This is a form of positive tropism since plants will grow towards light. Auxins will move away from the light- so the part facing away from the light will grow faster. This results in the plant growing towards the light.

Geotropism

Geotropism, or gravitropism is the directional growth of a plant based on the force of gravity. This is very important to the orientation of the plant since it is geotropism that causes the shoot to grow downwards against gravity (negative geotropism) and the roots to grow downwards with gravity.

How do auxins play into this when you place a plant on its side?

Answer: Auxins tend to move to the bottom part of the plant when it’s laid on its side due to gravity pulling everything down. In the stem, the extra auxins on the lower side make the cells grow faster, so the stem starts to bend upward. This is known as the geotropism. In roots, auxins also gather on the lower side, but they slow down cell growth there. This makes the upper side grow faster, so the roots bend downward, toward gravity.

Hydrotropism

Hydrotropism is the growth of a plant in the direction of water. Plants will exhibit either positive hydrotropism to find water in protection against droughts, or negative hydrotropism to avoid areas over-saturated with water. The cells on the side of the root closest to the water source experience slower growth than those on the opposite side

Responses of green plants to stimuli

Plants respond to stimuli by making part movement or growth movement, which aids in survival.

Part movements

• Leaves of some plants fold up when they are touched or hit by strong winds to protect themselves, like the mimosa.

• Leaves of other plants fold at night and open in the morning to catch sunlight for energy, like the tamarind.

• Flowers of some plants open in the morning to help pollination (when pollen moves between flowers), and close at night, like the hibiscus.

These movements happen because of changes in the water pressure inside the plant cells.

Growth movements

• Shoots (the parts of plants that grow upwards) grow towards light. (positive phototropism). This helps them get more light which they need for photosynthesis. If there’s no light or the light is even from all sides of the plant shoots grow upwards fighting against gravity. (negative geotropism). Growing upward also helps the plant put flowers in the best spot for pollination and spreading seeds.

• Roots grow downward because of gravity. This helps them stay in the soil and collect water and minerals. Roots also grow towards water, which is important for photosynthesis and the plant's survival.

• Roots respond negatively to light and grow away from it (negative phototropism). They grow towards gravity (positive geotropism)

• Roots grow downwards in search of water.

Irritability in Invertebrates

Eg: worms, millipedes, centipedes, woodlice

• These all have endoskeletons made from fluid. They move by shifting the fluid from place to place.

• They tend to migrate to habitats which have the most suitable conditions. These habitats are warm, moist and dark

- They prefer moist environments because they breathe through their skin.

- They like warmth is required for their enzymes to get the optimum temperature

- The dark: to avoid beings seen by predators

• They also feed on dead plant matter. They are usually found under rocks, under leaves etc.

Types of muscles

There are 3 types of muscles: voluntary, involuntary and cardiac muscle.

1. smooth muscle – found in the internal organs and blood vessels - this is involuntary

2. cardiac muscle – found only in the heart - this is involuntary

3. skeletal muscle – attached to the skeleton - this is voluntary

Involuntary muscles are not under our conscious control which means we can't make them contract when we think about it.

Voluntary muscles are under our conscious control so we can move these muscles when we want to. These are the muscles we use to make all the movements needed in physical activity and sports.

Skeletal muscles

• Muscles can only contract and relax.

• The ends of skeletal muscles are attached to bones by a tough elastic tissue called tendons.

• Muscles can pull but never push.

• They pull only when they contract. When it is contracted, its length is shortened.

• When returning to their original length, they relax (NOT 'expand')

Antagonistic pairs

• Muscles are arranged in antagonistic pairs.

• The pair of muscles are arranged in such a way that when one contracts, it produces an opposite effect on the other muscle in the pair, E.g.: the biceps and triceps muscles in the human arm.

• When a muscle contracts and flexes the joint (flexor), the other muscle relaxes and straightens the joint (extensor)

Types of joints

Joints are formed where two bones meet.

Tendon –connects muscle to bone.

The joints may be fibrous joints (fused), moveable joints (synovial), ball and socket joints and hinge joints.

Fibrous joints

Fibrous joints can be found in the skull and pelvis, where several bones have fused to form a rigid structure. The joints in the skull are called sutures.

Cartilaginous joints

Cartilaginous joints are a type of joint where the bones are entirely joined by cartilage.

Ball and socket joints

• Found in the hip bone and shoulder

• Allows the most movement of all the joints (move in all directions) that is 360

Hinge joint

• Found in the elbow and the knee.

• Allow bones to move back and forth, like a hinge in a door (move in 1 direction)

Synovial Joint

The functions of the structures in a synovial joint are:

• Cartilage - covers the ends of bones. It is smooth and acts as a shock absorber and stops the 2 bones from rubbing together

• Synovial membrane - encloses the joint and secretes synovial fluid

• Synovial fluid - serves to lubricate the joints and makes movement easy

• Ligaments - tough elastic stands that hold 2 bones together at the joints and prevent dislocation

Irritability in Humans

Irritability – the capacity of living cells to respond to stimuli.

Stimulus – a change in the environment.

Response - change in an organism or part of an organism which is brought about by a stimulus.

Receptor – the part of the organism that detects the stimulus.

Effector – the part of the organisms that respond to the stimulus.

Humans have two coordination systems:

1. Nervous system – made up of nerves.

2. Endocrine system – made up of organs which secrete hormones eg: adrenaline and insulin into the blood.

Nervous System

The human nervous system is divided into 2 parts: 1. Central nervous system and 2. Peripheral nervous system

• The CNS consists of the brain and spinal cord

• The PNS consists of cranial nerves and spinal nerves

Neurones

These are specialized cells that transmit messages called nerve impulses throughout

the nervous system.

Neurons consist of a cell body and thin structures called nerve fibres that extend from it.

Types of Neurones

There are three types of neurones: sensory neurons, relay and motor neurons.

1. Sensory neurones carry impulses from sense organs to the CNS (brain or spinal cord). For example: Rods and cones in the eye.

2. Relay neurones are found inside the CNS and connect sensory and motor neurones. For example: muscles and glands such as sweat glands and the adrenal glands.

3. Motor neurones carry impulses from the CNS to effectors (muscles or glands)

Differences between tendon and ligament and their functions

Tendons connect muscles to bones and help with movement. Whereas Ligaments connect bones to other bones and support the joints.

Pivot joint

A pivot joint is a type of joint in the human body that allows a body part to rotate around a single axis.

Structure: A cylinder-shaped bone rotates inside a ring-shaped bone or ligament

Movement: The moving bone rotates around its own axis

Examples: The joint between the atlas and axis in the neck, and the joint in the wrist that allows the palm to turn up and down

Pivot joints are a type of synovial joint, which means they are freely moveable joints where the ends of two bones connect.

Reflex Arc

When a receptor detects a stimulus, nerve cells known as neurons carry the signal from the stimulated receptor to the central nervous system to the correct effector. A sensory neuron carries the message from the receptor to the central nervous system (the spinal cord and brain). A motor neuron carries the message from the central nervous system to the effector. This is known as a reflex arc.

1. The stimulus, a tap below the knee, is delivered using a hammer

2. The stretch receptor in the quadriceps is stimulated

3. Impulses travel along a sensory neuron to the spinal cord

4. Impulses travel directly into a motor neuron in the spinal cord

5. Impulses move along the motor neuron to the extensor muscle of the leg

6. The extensor muscle contracts, causing the lower leg to rise (knee jerk)

Q1: What happens when a doctor taps the knee?

When a doctor taps the knee, they are checking for something called the knee jerk reflex. This taps the tendon which is a band of tissue below the kneecap. It stretches the tendon and also the muscle connected to it. The nerves in the knee send signals to the spinal cord instantly which then sends a signal to the muscle to make it contract, This causes the lower leg to kick out quickly.

Q2: Why might a person's knee not respond?

A person’s knee might not respond when tapped and there are several reasons for this.

1. There could be an issue with the nervous in the leg. They may be damaged which is why they aren’t able to send signals properly.

2. Age can play a role in the reflex response. It may be weaker or slower due to natural changes in nerves and muscles over time.